diff --git a/appinfo/info.xml b/appinfo/info.xml
index 084081a1bc..9bbb462eae 100644
--- a/appinfo/info.xml
+++ b/appinfo/info.xml
@@ -29,7 +29,7 @@ The rating depends on the installed text processing backend. See [the rating ove
 
 Learn more about the Nextcloud Ethical AI Rating [in our blog](https://nextcloud.com/blog/nextcloud-ethical-ai-rating/).
 	]]></description>
-	<version>3.6.0-alpha.1</version>
+	<version>3.6.0-alpha.2</version>
 	<licence>agpl</licence>
 	<author>Christoph Wurst</author>
 	<author homepage="https://github.com/nextcloud/groupware">Nextcloud Groupware Team</author>
diff --git a/appinfo/routes.php b/appinfo/routes.php
index 688279f9bf..c2879df576 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -450,7 +450,21 @@
 			'url' => '/api/drafts/move/{id}',
 			'verb' => 'POST',
 		],
-
+		[
+			'name' => 'outOfOffice#getState',
+			'url' => '/api/out-of-office/{accountId}',
+			'verb' => 'GET',
+		],
+		[
+			'name' => 'outOfOffice#update',
+			'url' => '/api/out-of-office/{accountId}',
+			'verb' => 'POST',
+		],
+		[
+			'name' => 'outOfOffice#followSystem',
+			'url' => '/api/out-of-office/{accountId}/follow-system',
+			'verb' => 'POST',
+		],
 	],
 	'resources' => [
 		'accounts' => ['url' => '/api/accounts'],
diff --git a/lib/AppInfo/Application.php b/lib/AppInfo/Application.php
index dd71aa309e..d23e95fb6e 100644
--- a/lib/AppInfo/Application.php
+++ b/lib/AppInfo/Application.php
@@ -66,6 +66,7 @@
 use OCA\Mail\Listener\MoveJunkListener;
 use OCA\Mail\Listener\NewMessageClassificationListener;
 use OCA\Mail\Listener\OauthTokenRefreshListener;
+use OCA\Mail\Listener\OutOfOfficeListener;
 use OCA\Mail\Listener\SaveSentMessageListener;
 use OCA\Mail\Listener\SpamReportListener;
 use OCA\Mail\Listener\UserDeletedListener;
@@ -88,6 +89,8 @@
 use OCP\Dashboard\IAPIWidgetV2;
 use OCP\IServerContainer;
 use OCP\Search\IFilteringProvider;
+use OCP\User\Events\OutOfOfficeEndedEvent;
+use OCP\User\Events\OutOfOfficeStartedEvent;
 use OCP\User\Events\UserDeletedEvent;
 use OCP\Util;
 use Psr\Container\ContainerInterface;
@@ -142,6 +145,13 @@ public function register(IRegistrationContext $context): void {
 		$context->registerEventListener(SynchronizationEvent::class, AccountSynchronizedThreadUpdaterListener::class);
 		$context->registerEventListener(UserDeletedEvent::class, UserDeletedListener::class);
 
+		// TODO: drop condition if nextcloud < 28 is not supported anymore
+		if (class_exists(OutOfOfficeStartedEvent::class)
+		 && class_exists(OutOfOfficeEndedEvent::class)) {
+			$context->registerEventListener(OutOfOfficeStartedEvent::class, OutOfOfficeListener::class);
+			$context->registerEventListener(OutOfOfficeEndedEvent::class, OutOfOfficeListener::class);
+		}
+
 		$context->registerMiddleWare(ErrorMiddleware::class);
 		$context->registerMiddleWare(ProvisioningMiddleware::class);
 
diff --git a/lib/Controller/OutOfOfficeController.php b/lib/Controller/OutOfOfficeController.php
new file mode 100644
index 0000000000..c6ceb31870
--- /dev/null
+++ b/lib/Controller/OutOfOfficeController.php
@@ -0,0 +1,178 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Controller;
+
+use DateTimeImmutable;
+use OCA\Mail\AppInfo\Application;
+use OCA\Mail\Exception\ServiceException;
+use OCA\Mail\Http\JsonResponse;
+use OCA\Mail\Http\TrapError;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+use OCA\Mail\Service\OutOfOfficeService;
+use OCP\AppFramework\Controller;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IRequest;
+use OCP\IUserSession;
+use OCP\User\IAvailabilityCoordinator;
+use Psr\Container\ContainerExceptionInterface;
+use Psr\Container\ContainerInterface;
+
+class OutOfOfficeController extends Controller {
+	private ?IAvailabilityCoordinator $availabilityCoordinator;
+
+	public function __construct(
+		IRequest $request,
+		ContainerInterface $container,
+		private IUserSession $userSession,
+		private AccountService $accountService,
+		private OutOfOfficeService $outOfOfficeService,
+		private ITimeFactory $timeFactory,
+	) {
+		parent::__construct(Application::APP_ID, $request);
+
+		try {
+			$this->availabilityCoordinator = $container->get(IAvailabilityCoordinator::class);
+		} catch (ContainerExceptionInterface) {
+			$this->availabilityCoordinator = null;
+		}
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 */
+	#[TrapError]
+	public function getState(int $accountId): JsonResponse {
+		$user = $this->userSession->getUser();
+		if ($user === null) {
+			return JsonResponse::fail([], Http::STATUS_FORBIDDEN);
+		}
+
+		$account = $this->accountService->findById($accountId);
+		if ($account->getUserId() !== $user->getUID()) {
+			return JsonResponse::fail([], Http::STATUS_NOT_FOUND);
+		}
+
+		$state = $this->outOfOfficeService->parseState($account->getMailAccount());
+		return JsonResponse::success($state);
+	}
+
+	/**
+	 * @NoAdminRequired
+	 */
+	#[TrapError]
+	public function followSystem(int $accountId) {
+		if ($this->availabilityCoordinator === null) {
+			return JsonResponse::fail([], Http::STATUS_NOT_IMPLEMENTED);
+		}
+
+		$user = $this->userSession->getUser();
+		if ($user === null) {
+			return JsonResponse::fail([], Http::STATUS_FORBIDDEN);
+		}
+
+		$account = $this->accountService->findById($accountId);
+		if ($account->getUserId() !== $user->getUID()) {
+			return JsonResponse::fail([], Http::STATUS_NOT_FOUND);
+		}
+
+		$mailAccount = $account->getMailAccount();
+		if (!$mailAccount->getOutOfOfficeFollowsSystem()) {
+			$mailAccount->setOutOfOfficeFollowsSystem(true);
+			$this->accountService->update($mailAccount);
+		}
+
+		$state = null;
+		$now = $this->timeFactory->getTime();
+		$currentOutOfOfficeData = $this->availabilityCoordinator->getCurrentOutOfOfficeData($user);
+		if ($currentOutOfOfficeData !== null
+		 && $currentOutOfOfficeData->getStartDate() <= $now
+		 && $currentOutOfOfficeData->getEndDate() > $now) {
+			// In the middle of a running absence => enable auto responder
+			$state = new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("@" . $currentOutOfOfficeData->getStartDate()),
+				new DateTimeImmutable("@" . $currentOutOfOfficeData->getEndDate()),
+				$currentOutOfOfficeData->getShortMessage(),
+				$currentOutOfOfficeData->getMessage(),
+			);
+			$this->outOfOfficeService->update($mailAccount, $state);
+		} else {
+			// Absence has not yet started or has already ended => disable auto responder
+			$this->outOfOfficeService->disable($mailAccount);
+		}
+
+		return JsonResponse::success($state);
+	}
+
+	/**
+	 * @NoAdminRequired
+	 */
+	#[TrapError]
+	public function update(
+		int $accountId,
+		bool $enabled,
+		?string $start,
+		?string $end,
+		string $subject,
+		string $message,
+	): JsonResponse {
+		$user = $this->userSession->getUser();
+		if ($user === null) {
+			return JsonResponse::fail([], Http::STATUS_FORBIDDEN);
+		}
+
+		$account = $this->accountService->findById($accountId);
+		if ($account->getUserId() !== $user->getUID()) {
+			return JsonResponse::fail([], Http::STATUS_NOT_FOUND);
+		}
+
+		if ($enabled && $start === null) {
+			throw new ServiceException("Missing start date");
+		}
+
+		$mailAccount = $account->getMailAccount();
+		if ($mailAccount->getOutOfOfficeFollowsSystem()) {
+			$mailAccount->setOutOfOfficeFollowsSystem(false);
+			$this->accountService->update($mailAccount);
+		}
+
+		$state = new OutOfOfficeState(
+			$enabled,
+			$start ? new DateTimeImmutable($start) : null,
+			$end ? new DateTimeImmutable($end) : null,
+			$subject,
+			$message,
+		);
+		$this->outOfOfficeService->update($mailAccount, $state);
+
+		$newState = $this->outOfOfficeService->parseState($mailAccount);
+		return JsonResponse::success($newState);
+	}
+}
diff --git a/lib/Controller/PageController.php b/lib/Controller/PageController.php
index 1764f6b229..743dd9c03f 100644
--- a/lib/Controller/PageController.php
+++ b/lib/Controller/PageController.php
@@ -53,6 +53,9 @@
 use OCP\IURLGenerator;
 use OCP\IUserManager;
 use OCP\IUserSession;
+use OCP\User\IAvailabilityCoordinator;
+use Psr\Container\ContainerExceptionInterface;
+use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
 use Throwable;
 use function class_exists;
@@ -77,6 +80,7 @@ class PageController extends Controller {
 	private SmimeService $smimeService;
 	private AiIntegrationsService $aiIntegrationsService;
 	private IUserManager $userManager;
+	private ?IAvailabilityCoordinator $availabilityCoordinator;
 
 	public function __construct(string $appName,
 		IRequest $request,
@@ -96,7 +100,8 @@ public function __construct(string $appName,
 		ICredentialStore $credentialStore,
 		SmimeService     $smimeService,
 		AiIntegrationsService $aiIntegrationsService,
-		IUserManager $userManager, ) {
+		IUserManager $userManager,
+		ContainerInterface $container) {
 		parent::__construct($appName, $request);
 
 		$this->urlGenerator = $urlGenerator;
@@ -116,6 +121,12 @@ public function __construct(string $appName,
 		$this->smimeService = $smimeService;
 		$this->aiIntegrationsService = $aiIntegrationsService;
 		$this->userManager = $userManager;
+
+		try {
+			$this->availabilityCoordinator = $container->get(IAvailabilityCoordinator::class);
+		} catch (ContainerExceptionInterface $e) {
+			$this->availabilityCoordinator = null;
+		}
 	}
 
 	/**
@@ -174,7 +185,7 @@ public function index(): TemplateResponse {
 			'sort-order',
 			$this->preferences->getPreference($this->currentUserId, 'sort-order', 'newest')
 		);
-		
+
 		try {
 			$password = $this->credentialStore->getLoginCredentials()->getPassword();
 			$passwordIsUnavailable = $password === null || $password === '';
@@ -277,6 +288,13 @@ function (SmimeCertificate $certificate) {
 			),
 		);
 
+		if ($this->availabilityCoordinator !== null) {
+			$this->initialStateService->provideInitialState(
+				'enable-system-out-of-office',
+				$this->availabilityCoordinator->isEnabled(),
+			);
+		}
+
 		$csp = new ContentSecurityPolicy();
 		$csp->addAllowedFrameDomain('\'self\'');
 		$response->setContentSecurityPolicy($csp);
diff --git a/lib/Controller/SieveController.php b/lib/Controller/SieveController.php
index 2bfb68e6ea..54ca93e476 100644
--- a/lib/Controller/SieveController.php
+++ b/lib/Controller/SieveController.php
@@ -4,6 +4,7 @@
 
 /**
  * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
  *
  * Mail
  *
@@ -30,7 +31,7 @@
 use OCA\Mail\Exception\CouldNotConnectException;
 use OCA\Mail\Http\JsonResponse as MailJsonResponse;
 use OCA\Mail\Http\TrapError;
-use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\SieveService;
 use OCA\Mail\Sieve\SieveClientFactory;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Db\DoesNotExistException;
@@ -42,7 +43,6 @@
 use Psr\Log\LoggerInterface;
 
 class SieveController extends Controller {
-	private AccountService $accountService;
 	private MailAccountMapper $mailAccountMapper;
 	private SieveClientFactory $sieveClientFactory;
 	private string $currentUserId;
@@ -52,16 +52,15 @@ class SieveController extends Controller {
 
 	public function __construct(IRequest $request,
 		string $UserId,
-		AccountService $accountService,
 		MailAccountMapper $mailAccountMapper,
 		SieveClientFactory $sieveClientFactory,
 		ICrypto $crypto,
 		IRemoteHostValidator $hostValidator,
-		LoggerInterface $logger
+		LoggerInterface $logger,
+		private SieveService $sieveService,
 	) {
 		parent::__construct(Application::APP_ID, $request);
 		$this->currentUserId = $UserId;
-		$this->accountService = $accountService;
 		$this->mailAccountMapper = $mailAccountMapper;
 		$this->sieveClientFactory = $sieveClientFactory;
 		$this->crypto = $crypto;
@@ -78,21 +77,14 @@ public function __construct(IRequest $request,
 	 *
 	 * @throws CouldNotConnectException
 	 * @throws ClientException
+	 * @throws ManagesieveException
 	 */
 	#[TrapError]
 	public function getActiveScript(int $id): JSONResponse {
-		$sieve = $this->getClient($id);
-
-		$scriptName = $sieve->getActive();
-		if ($scriptName === null) {
-			$script = '';
-		} else {
-			$script = $sieve->getScript($scriptName);
-		}
-
+		$activeScript = $this->sieveService->getActiveScript($this->currentUserId, $id);
 		return new JSONResponse([
-			'scriptName' => $scriptName,
-			'script' => $script,
+			'scriptName' => $activeScript->getName(),
+			'script' => $activeScript->getScript(),
 		]);
 	}
 
@@ -106,16 +98,11 @@ public function getActiveScript(int $id): JSONResponse {
 	 *
 	 * @throws ClientException
 	 * @throws CouldNotConnectException
-	 * @throws ManagesieveException
 	 */
 	#[TrapError]
 	public function updateActiveScript(int $id, string $script): JSONResponse {
-		$sieve = $this->getClient($id);
-
-		$scriptName = $sieve->getActive() ?? 'nextcloud';
-
 		try {
-			$sieve->installScript($scriptName, $script, true);
+			$this->sieveService->updateActiveScript($this->currentUserId, $id, $script);
 		} catch (ManagesieveException $e) {
 			$this->logger->error('Installing sieve script failed: ' . $e->getMessage(), ['app' => 'mail', 'exception' => $e]);
 			return new JSONResponse(data: ['message' => $e->getMessage()], statusCode: Http::STATUS_UNPROCESSABLE_ENTITY);
@@ -200,28 +187,4 @@ public function updateAccount(int $id,
 		$this->mailAccountMapper->save($mailAccount);
 		return new JSONResponse(['sieveEnabled' => $mailAccount->isSieveEnabled()]);
 	}
-
-	/**
-	 * @param int $id
-	 *
-	 * @return \Horde\ManageSieve
-	 *
-	 * @throws ClientException
-	 * @throws CouldNotConnectException
-	 */
-	protected function getClient(int $id): \Horde\ManageSieve {
-		$account = $this->accountService->find($this->currentUserId, $id);
-
-		if (!$account->getMailAccount()->isSieveEnabled()) {
-			throw new ClientException('ManageSieve is disabled.');
-		}
-
-		try {
-			$sieve = $this->sieveClientFactory->getClient($account);
-		} catch (ManagesieveException $e) {
-			throw new CouldNotConnectException($e, 'ManageSieve', $account->getMailAccount()->getSieveHost(), $account->getMailAccount()->getSievePort());
-		}
-
-		return $sieve;
-	}
 }
diff --git a/lib/Db/MailAccount.php b/lib/Db/MailAccount.php
index 3744b1414a..3fd86b4e14 100644
--- a/lib/Db/MailAccount.php
+++ b/lib/Db/MailAccount.php
@@ -116,6 +116,8 @@
  * @method void setJunkMailboxId(?int $id)
  * @method bool getSearchBody()
  * @method void setSearchBody(bool $searchBody)
+ * @method bool|null getOooFollowsSystem()
+ * @method void setOooFollowsSystem(bool $oooFollowsSystem)
  */
 class MailAccount extends Entity {
 	public const SIGNATURE_MODE_PLAIN = 0;
@@ -195,6 +197,9 @@ class MailAccount extends Entity {
 	/** @var bool */
 	protected $searchBody = false;
 
+	/** @var bool|null */
+	protected $oooFollowsSystem;
+
 	/**
 	 * @param array $params
 	 */
@@ -249,6 +254,9 @@ public function __construct(array $params = []) {
 		if (isset($params['trashRetentionDays'])) {
 			$this->setTrashRetentionDays($params['trashRetentionDays']);
 		}
+		if (isset($params['outOfOfficeFollowsSystem'])) {
+			$this->setOutOfOfficeFollowsSystem($params['outOfOfficeFollowsSystem']);
+		}
 
 		$this->addType('inboundPort', 'integer');
 		$this->addType('outboundPort', 'integer');
@@ -271,6 +279,15 @@ public function __construct(array $params = []) {
 		$this->addType('trashRetentionDays', 'integer');
 		$this->addType('junkMailboxId', 'integer');
 		$this->addType('searchBody', 'boolean');
+		$this->addType('oooFollowsSystem', 'boolean');
+	}
+
+	public function getOutOfOfficeFollowsSystem(): bool {
+		return $this->getOooFollowsSystem() === true;
+	}
+
+	public function setOutOfOfficeFollowsSystem(bool $outOfOfficeFollowsSystem): void {
+		$this->setOooFollowsSystem($outOfOfficeFollowsSystem);
 	}
 
 	/**
@@ -305,6 +322,7 @@ public function toJson() {
 			'trashRetentionDays' => $this->getTrashRetentionDays(),
 			'junkMailboxId' => $this->getJunkMailboxId(),
 			'searchBody' => $this->getSearchBody(),
+			'outOfOfficeFollowsSystem' => $this->getOutOfOfficeFollowsSystem(),
 		];
 
 		if (!is_null($this->getOutboundHost())) {
diff --git a/lib/Exception/OutOfOfficeParserException.php b/lib/Exception/OutOfOfficeParserException.php
new file mode 100644
index 0000000000..08eceea2b6
--- /dev/null
+++ b/lib/Exception/OutOfOfficeParserException.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Exception;
+
+use Exception;
+
+class OutOfOfficeParserException extends Exception {
+}
diff --git a/lib/Listener/OutOfOfficeListener.php b/lib/Listener/OutOfOfficeListener.php
new file mode 100644
index 0000000000..b5c62c361b
--- /dev/null
+++ b/lib/Listener/OutOfOfficeListener.php
@@ -0,0 +1,81 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Listener;
+
+use DateTimeImmutable;
+use Exception;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+use OCA\Mail\Service\OutOfOfficeService;
+use OCP\EventDispatcher\Event;
+use OCP\EventDispatcher\IEventListener;
+use OCP\User\Events\OutOfOfficeEndedEvent;
+use OCP\User\Events\OutOfOfficeStartedEvent;
+use Psr\Log\LoggerInterface;
+
+/**
+ * @template-implements IEventListener<Event|OutOfOfficeStartedEvent|OutOfOfficeEndedEvent>
+ */
+class OutOfOfficeListener implements IEventListener {
+	public function __construct(
+		private AccountService $accountService,
+		private OutOfOfficeService $outOfOfficeService,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	public function handle(Event $event): void {
+		if (!($event instanceof OutOfOfficeStartedEvent) && !($event instanceof OutOfOfficeEndedEvent)) {
+			return;
+		}
+
+		$eventData = $event->getData();
+		$accounts = $this->accountService->findByUserId($event->getData()->getUser()->getUID());
+		foreach ($accounts as $account) {
+			if (!$account->getMailAccount()->getOutOfOfficeFollowsSystem()) {
+				continue;
+			}
+
+			$state = new OutOfOfficeState(
+				($event instanceof OutOfOfficeStartedEvent),
+				new DateTimeImmutable('@' . $eventData->getStartDate()),
+				new DateTimeImmutable('@' . $eventData->getEndDate()),
+				$eventData->getShortMessage(),
+				$eventData->getMessage(),
+			);
+			try {
+				$this->outOfOfficeService->update($account->getMailAccount(), $state);
+			} catch (Exception $e) {
+				$this->logger->error('Failed to apply out-of-office sieve script: ' . $e->getMessage(), [
+					'exception' => $e,
+					'userId' => $account->getUserId(),
+					'accountId' => $account->getId(),
+				]);
+			}
+		}
+	}
+}
diff --git a/lib/Migration/Version3500Date20231114180656.php b/lib/Migration/Version3500Date20231114180656.php
new file mode 100644
index 0000000000..f01b6c39f2
--- /dev/null
+++ b/lib/Migration/Version3500Date20231114180656.php
@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+class Version3500Date20231114180656 extends SimpleMigrationStep {
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		$accountsTable = $schema->getTable('mail_accounts');
+		if (!$accountsTable->hasColumn('ooo_follows_system')) {
+			$accountsTable->addColumn('ooo_follows_system', Types::BOOLEAN, [
+				'notnull' => false,
+				'default' => false,
+			]);
+		}
+
+		return $schema;
+	}
+}
diff --git a/lib/Service/OutOfOffice/OutOfOfficeParser.php b/lib/Service/OutOfOffice/OutOfOfficeParser.php
new file mode 100644
index 0000000000..4b98d3a00e
--- /dev/null
+++ b/lib/Service/OutOfOffice/OutOfOfficeParser.php
@@ -0,0 +1,201 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Service\OutOfOffice;
+
+use DateTimeImmutable;
+use JsonException;
+use OCA\Mail\Exception\OutOfOfficeParserException;
+
+/**
+ * Parses and builds out-of-office states from/to sieve scripts.
+ */
+class OutOfOfficeParser {
+	private const SEPARATOR = '### Nextcloud Mail: Vacation Responder ### DON\'T EDIT ###';
+	private const DATA_MARKER = '# DATA: ';
+
+	private const STATE_COPY = 0;
+	private const STATE_SKIP = 1;
+
+	/**
+	 * @throws OutOfOfficeParserException
+	 */
+	public function parseOutOfOfficeState(string $sieveScript): OutOfOfficeParserResult {
+		$data = null;
+		$scriptOut = [];
+
+		$state = self::STATE_COPY;
+		$nextState = $state;
+
+		$lines = preg_split('/\r?\n/', $sieveScript);
+		foreach ($lines as $line) {
+			switch ($state) {
+				case self::STATE_COPY:
+					if (str_starts_with($line, self::SEPARATOR)) {
+						$nextState = self::STATE_SKIP;
+					} else {
+						$scriptOut[] = $line;
+					}
+					break;
+				case self::STATE_SKIP:
+					if (str_starts_with($line, self::SEPARATOR)) {
+						$nextState = self::STATE_COPY;
+					} elseif (str_starts_with($line, self::DATA_MARKER)) {
+						$json = substr($line, strlen(self::DATA_MARKER));
+						try {
+							$jsonData = json_decode($json, true, 10, JSON_THROW_ON_ERROR);
+						} catch (JsonException $e) {
+							throw new OutOfOfficeParserException(
+								'Failed to parse out-of-office state json: ' . $e->getMessage(),
+								0,
+								$e,
+							);
+						}
+						$data = OutOfOfficeState::fromJson($jsonData);
+					}
+					break;
+				default:
+					throw new OutOfOfficeParserException('Reached an invalid state');
+			}
+			$state = $nextState;
+		}
+
+		return new OutOfOfficeParserResult($data, $sieveScript, implode("\n", $scriptOut));
+	}
+
+	/**
+	 * @param string[] $allowedRecipients Respond to envelopes that are addressed to the given addresses.
+	 *								      Should be the main address and aliases of the account.
+	 *                                    An empty array will leave the decision to the sieve implementation.
+	 *
+	 * @throws OutOfOfficeParserException If the given out-of-office state is missing required fields.
+	 * @throws JSONException If the given out-of-office state can't be serialized to JSON.
+	 */
+	public function buildSieveScript(
+		OutOfOfficeState $state,
+		string $untouchedScript,
+		array $allowedRecipients,
+	): string {
+		// No need to persist dates if not enabled
+		if (!$state->isEnabled()) {
+			$state->setStart(null);
+			$state->setEnd(null);
+		}
+
+		$stateJsonString = json_encode($state, JSON_THROW_ON_ERROR);
+
+		if (!$state->isEnabled()) {
+			//unset($jsonData['start'], $jsonString['end']);
+			return implode("\n", [
+				$untouchedScript,
+				self::SEPARATOR,
+				self::DATA_MARKER . $stateJsonString,
+				self::SEPARATOR,
+			]);
+		}
+
+		if ($state->getStart() === null) {
+			throw new OutOfOfficeParserException('Out-of-office state is missing a start date');
+		}
+
+		$formattedStart = $this->formatDateForSieve($state->getStart());
+		if ($state->getEnd() !== null) {
+			$formattedEnd = $this->formatDateForSieve($state->getEnd());
+			$condition = "allof(currentdate :value \"ge\" \"date\" \"$formattedStart\", currentdate :value \"le\" \"date\" \"$formattedEnd\")";
+		} else {
+			$condition = "currentdate :value \"ge\" \"date\" \"$formattedStart\"";
+		}
+
+		$escapedSubject = $this->escapeStringForSieve($state->getSubject());
+		$vacation = [
+			'vacation',
+			':days 4',
+			":subject \"$escapedSubject\"",
+		];
+
+		if (!empty($allowedRecipients)) {
+			$formattedRecipients = array_map(static function (string $recipient) {
+				return "\"$recipient\"";
+			}, $allowedRecipients);
+			$joinedRecipients = implode(', ', $formattedRecipients);
+			$vacation[] = ":addresses [$joinedRecipients]";
+		}
+
+		$escapedMessage = $this->escapeStringForSieve($state->getMessage());
+		$vacation[] = "\"$escapedMessage\"";
+		$vacationCommand = implode(' ', $vacation);
+
+		$subjectSection = [
+			'set "subject" "";',
+			'if header :matches "subject" "*" {',
+			"\tset \"subject\" \"\${1}\";",
+			'}',
+		];
+
+		$hasSubjectPlaceholder = str_contains($state->getSubject(), '${subject}')
+			|| str_contains($state->getMessage(), '${subject}');
+
+		$requireSection = [
+			self::SEPARATOR,
+			'require "date";',
+			'require "relational";',
+			'require "vacation";',
+		];
+		if ($hasSubjectPlaceholder) {
+			$requireSection[] = 'require "variables";';
+		}
+		$requireSection[] = self::SEPARATOR;
+
+		$vacationSection = [
+			self::SEPARATOR,
+			self::DATA_MARKER . $stateJsonString,
+		];
+		if ($hasSubjectPlaceholder) {
+			$vacationSection = array_merge($vacationSection, $subjectSection);
+		}
+		$vacationSection = array_merge($vacationSection, [
+			"if $condition {",
+			"\t$vacationCommand;",
+			'}',
+			self::SEPARATOR,
+		]);
+
+		return implode("\n", array_merge(
+			$requireSection,
+			[$untouchedScript],
+			$vacationSection,
+		));
+	}
+
+	private function formatDateForSieve(DateTimeImmutable $date): string {
+		return $date->format('Y-m-d');
+	}
+
+	private function escapeStringForSieve(string $subject): string {
+		$subject = preg_replace('/\\\\/', '\\\\\\\\', $subject);
+		return preg_replace('/"/', '\\"', $subject);
+	}
+}
diff --git a/lib/Service/OutOfOffice/OutOfOfficeParserResult.php b/lib/Service/OutOfOffice/OutOfOfficeParserResult.php
new file mode 100644
index 0000000000..560e38c7fd
--- /dev/null
+++ b/lib/Service/OutOfOffice/OutOfOfficeParserResult.php
@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Service\OutOfOffice;
+
+use JsonSerializable;
+use ReturnTypeWillChange;
+
+class OutOfOfficeParserResult implements JsonSerializable {
+	public function __construct(
+		private ?OutOfOfficeState $state,
+		private string $sieveScript,
+		private string $untouchedSieveScript,
+	) {
+	}
+
+	public function getState(): ?OutOfOfficeState {
+		return $this->state;
+	}
+
+	public function getSieveScript(): string {
+		return $this->sieveScript;
+	}
+
+	public function getUntouchedSieveScript(): string {
+		return $this->untouchedSieveScript;
+	}
+
+	#[ReturnTypeWillChange]
+	public function jsonSerialize() {
+		return [
+			'state' => $this->getState()?->jsonSerialize(),
+			'script' => $this->getSieveScript(),
+			'untouchedScript' => $this->getUntouchedSieveScript(),
+		];
+	}
+}
diff --git a/lib/Service/OutOfOffice/OutOfOfficeState.php b/lib/Service/OutOfOffice/OutOfOfficeState.php
new file mode 100644
index 0000000000..2a774292fb
--- /dev/null
+++ b/lib/Service/OutOfOffice/OutOfOfficeState.php
@@ -0,0 +1,126 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Service\OutOfOffice;
+
+use DateTimeImmutable;
+use JsonSerializable;
+use ReturnTypeWillChange;
+
+class OutOfOfficeState implements JsonSerializable {
+	public const DEFAULT_VERSION = 1;
+
+	public function __construct(
+		private bool $enabled,
+		private ?DateTimeImmutable $start,
+		private ?DateTimeImmutable $end,
+		private string $subject,
+		private string $message,
+		private int $version = self::DEFAULT_VERSION,
+	) {
+	}
+
+	public static function fromJson(array $data): self {
+		return new self(
+			$data['enabled'],
+			isset($data['start']) ? new DateTimeImmutable($data['start']) : null,
+			isset($data['end']) ? new DateTimeImmutable($data['end']) : null,
+			$data['subject'],
+			$data['message'],
+			$data['version'],
+		);
+	}
+
+	public function getVersion(): int {
+		return $this->version;
+	}
+
+	public function setVersion(int $version): void {
+		$this->version = $version;
+	}
+
+	public function isEnabled(): bool {
+		return $this->enabled;
+	}
+
+	public function setEnabled(bool $enabled): void {
+		$this->enabled = $enabled;
+	}
+
+	public function getStart(): ?DateTimeImmutable {
+		return $this->start;
+	}
+
+	public function setStart(?DateTimeImmutable $start): void {
+		$this->start = $start;
+	}
+
+	public function getEnd(): ?DateTimeImmutable {
+		return $this->end;
+	}
+
+	public function setEnd(?DateTimeImmutable $end): void {
+		$this->end = $end;
+	}
+
+	public function getSubject(): string {
+		return $this->subject;
+	}
+
+	public function setSubject(string $subject): void {
+		$this->subject = $subject;
+	}
+
+	public function getMessage(): string {
+		return $this->message;
+	}
+
+	public function setMessage(string $message): void {
+		$this->message = $message;
+	}
+
+	#[ReturnTypeWillChange]
+	public function jsonSerialize() {
+		$json = [
+			'version' => $this->getVersion(),
+			'enabled' => $this->isEnabled(),
+		];
+
+		$start = $this->getStart();
+		if ($start) {
+			$json['start'] = $start->format('Y-m-d');
+		}
+
+		$end = $this->getEnd();
+		if ($end) {
+			$json['end'] = $end->format('Y-m-d');
+		}
+
+		$json['subject'] = $this->getSubject();
+		$json['message'] = $this->getMessage();
+		return $json;
+	}
+}
diff --git a/lib/Service/OutOfOfficeService.php b/lib/Service/OutOfOfficeService.php
new file mode 100644
index 0000000000..02f0b9a452
--- /dev/null
+++ b/lib/Service/OutOfOfficeService.php
@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Service;
+
+use Horde\ManageSieve\Exception as ManageSieveException;
+use JsonException;
+use OCA\Mail\Db\Alias;
+use OCA\Mail\Db\MailAccount;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\CouldNotConnectException;
+use OCA\Mail\Exception\OutOfOfficeParserException;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeParser;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeParserResult;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+use Psr\Log\LoggerInterface;
+
+class OutOfOfficeService {
+	public function __construct(
+		private OutOfOfficeParser $outOfOfficeParser,
+		private SieveService $sieveService,
+		private LoggerInterface $logger,
+		private AliasesService $aliasesService,
+	) {
+	}
+
+	/**
+	 * @throws ClientException
+	 * @throws OutOfOfficeParserException
+	 * @throws ManageSieveException
+	 * @throws CouldNotConnectException
+	 */
+	public function parseState(MailAccount $account): OutOfOfficeParserResult {
+		$script = $this->sieveService->getActiveScript($account->getUserId(), $account->getId());
+		return $this->outOfOfficeParser->parseOutOfOfficeState($script->getScript());
+	}
+
+	/**
+	 * @throws CouldNotConnectException
+	 * @throws JsonException
+	 * @throws ClientException
+	 * @throws OutOfOfficeParserException
+	 * @throws ManageSieveException
+	 */
+	public function update(MailAccount $account, OutOfOfficeState $state): void {
+		$script = $this->sieveService->getActiveScript($account->getUserId(), $account->getId());
+		$oldState = $this->outOfOfficeParser->parseOutOfOfficeState($script->getScript());
+		$newScript = $this->outOfOfficeParser->buildSieveScript(
+			$state,
+			$oldState->getUntouchedSieveScript(),
+			$this->buildAllowedRecipients($account),
+		);
+		try {
+			$this->sieveService->updateActiveScript($account->getUserId(), $account->getId(), $newScript);
+		} catch (ManageSieveException $e) {
+			$this->logger->error('Failed to save sieve script: ' . $e->getMessage(), [
+				'exception' => $e,
+				'script' => $newScript,
+			]);
+			throw $e;
+		}
+	}
+
+	/**
+	 * @throws ClientException
+	 * @throws OutOfOfficeParserException
+	 * @throws ManageSieveException
+	 * @throws CouldNotConnectException
+	 * @throws JsonException
+	 */
+	public function disable(MailAccount $account): void {
+		$state = $this->parseState($account)->getState();
+		if ($state === null || !$state->isEnabled()) {
+			return;
+		}
+
+		$state->setEnabled(false);
+		$this->update($account, $state);
+	}
+
+	/**
+	 * @return string[]
+	 */
+	private function buildAllowedRecipients(MailAccount $mailAccount): array {
+		$aliases = $this->aliasesService->findAll($mailAccount->getId(), $mailAccount->getUserId());
+		$formattedAliases = array_map(static function (Alias $alias) {
+			return $alias->getAlias();
+		}, $aliases);
+		return array_merge([$mailAccount->getEmail()], $formattedAliases);
+	}
+}
diff --git a/lib/Service/SieveService.php b/lib/Service/SieveService.php
new file mode 100644
index 0000000000..806dfecf52
--- /dev/null
+++ b/lib/Service/SieveService.php
@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Service;
+
+use Horde\ManageSieve\Exception as ManagesieveException;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\CouldNotConnectException;
+use OCA\Mail\Sieve\NamedSieveScript;
+use OCA\Mail\Sieve\SieveClientFactory;
+
+class SieveService {
+	public function __construct(
+		private SieveClientFactory $sieveClientFactory,
+		private AccountService $accountService,
+	) {
+	}
+
+	/**
+	 * @throws CouldNotConnectException
+	 * @throws ClientException
+	 * @throws ManagesieveException
+	 */
+	public function getActiveScript(string $userId, int $accountId): NamedSieveScript {
+		$sieve = $this->getClient($userId, $accountId);
+
+		$scriptName = $sieve->getActive();
+		if ($scriptName === null) {
+			$script = '';
+		} else {
+			$script = $sieve->getScript($scriptName);
+		}
+
+		// Sieve appends the script with a carriage return and line feed (\r\n) each time it's saved.
+		// Strip those line feeds to avoid the accumulation of unnecessary white space.
+		$script = rtrim($script, "\r\n");
+
+		return new NamedSieveScript($scriptName, $script);
+	}
+
+	/**
+	 * @throws ClientException
+	 * @throws CouldNotConnectException
+	 * @throws ManagesieveException
+	 */
+	public function updateActiveScript(string $userId, int $accountId, string $script): void {
+		$sieve = $this->getClient($userId, $accountId);
+
+		$scriptName = $sieve->getActive() ?? 'nextcloud';
+		$sieve->installScript($scriptName, $script, true);
+	}
+
+	/**
+	 * @throws ClientException
+	 * @throws CouldNotConnectException
+	 */
+	private function getClient(string $userId, int $accountId): \Horde\ManageSieve {
+		$account = $this->accountService->find($userId, $accountId);
+
+		if (!$account->getMailAccount()->isSieveEnabled()) {
+			throw new ClientException('ManageSieve is disabled');
+		}
+
+		try {
+			$sieve = $this->sieveClientFactory->getClient($account);
+		} catch (ManagesieveException $e) {
+			throw new CouldNotConnectException($e, 'ManageSieve', $account->getMailAccount()->getSieveHost(), $account->getMailAccount()->getSievePort());
+		}
+
+		return $sieve;
+	}
+}
diff --git a/lib/Sieve/NamedSieveScript.php b/lib/Sieve/NamedSieveScript.php
new file mode 100644
index 0000000000..350358995b
--- /dev/null
+++ b/lib/Sieve/NamedSieveScript.php
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Mail\Sieve;
+
+class NamedSieveScript {
+	public function __construct(
+		private ?string $name,
+		private string $script,
+	) {
+	}
+
+	public function getName(): ?string {
+		return $this->name;
+	}
+
+	public function getScript(): string {
+		return $this->script;
+	}
+}
diff --git a/package-lock.json b/package-lock.json
index 5bb4028905..3c6a5448e6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "nextcloud-mail",
-  "version": "3.6.0-alpha1",
+  "version": "3.6.0-alpha2",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "nextcloud-mail",
-      "version": "3.6.0-alpha1",
+      "version": "3.6.0-alpha2",
       "license": "agpl",
       "dependencies": {
         "@ckeditor/ckeditor5-alignment": "37.1.0",
diff --git a/package.json b/package.json
index 5a710b196d..96d61b6c77 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "nextcloud-mail",
   "description": "Nextcloud Mail",
-  "version": "3.6.0-alpha1",
+  "version": "3.6.0-alpha2",
   "author": "Christoph Wurst <christoph@winzerhof-wurst.at>",
   "license": "agpl",
   "private": true,
diff --git a/psalm.xml b/psalm.xml
index 644ab5e266..4286154ec1 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -47,6 +47,9 @@
 				<referencedClass name="OCP\TextProcessing\SummaryTaskType" />
 				<referencedClass name="OCP\TextProcessing\Task" />
 				<referencedClass name="OCP\TextProcessing\SummaryTaskType" />
+				<referencedClass name="OCP\User\Events\OutOfOfficeEndedEvent" />
+				<referencedClass name="OCP\User\Events\OutOfOfficeStartedEvent" />
+				<referencedClass name="OCP\User\IAvailabilityCoordinator" />
 			</errorLevel>
 		</UndefinedClass>
 		<UndefinedDocblockClass>
diff --git a/src/components/OutOfOfficeForm.vue b/src/components/OutOfOfficeForm.vue
index b26f103e98..2fbca730cc 100644
--- a/src/components/OutOfOfficeForm.vue
+++ b/src/components/OutOfOfficeForm.vue
@@ -21,8 +21,7 @@
   -->
 
 <template>
-	<!-- Wait until sieve script has been fetched before showing form. -->
-	<form v-if="sieveScriptData" class="form" @submit.prevent="submit">
+	<form class="form" @submit.prevent="submit">
 		<div class="form__multi-row">
 			<fieldset class="form__fieldset">
 				<input
@@ -30,8 +29,8 @@
 					class="radio"
 					type="radio"
 					name="enabled"
-					:checked="!enabled"
-					@change="enabled = false">
+					:checked="enabled === OOO_DISABLED"
+					@change="enabled = OOO_DISABLED">
 				<label for="ooo-disabled">{{ t('mail', 'Autoresponder off') }}</label>
 			</fieldset>
 
@@ -41,60 +40,82 @@
 					class="radio"
 					type="radio"
 					name="enabled"
-					:checked="enabled"
-					@change="enabled = true">
+					:checked="enabled === OOO_ENABLED"
+					@change="enabled = OOO_ENABLED">
 				<label for="ooo-enabled">{{ t('mail', 'Autoresponder on') }}</label>
 			</fieldset>
+
+			<fieldset v-if="hasPersonalAbsenceSettings" class="form__fieldset">
+				<input
+					id="ooo-follow-system"
+					class="radio"
+					type="radio"
+					name="enabled"
+					:checked="enabled === OOO_FOLLOW_SYSTEM"
+					@change="enabled = OOO_FOLLOW_SYSTEM">
+				<label for="ooo-follow-system">{{ t('mail', 'Autoresponder follows system settings') }}</label>
+			</fieldset>
 		</div>
 
-		<div class="form__multi-row">
+		<template v-if="followingSystem">
+			<p>{{ t('mail', 'The autoresponder follows your personal absence period settings.') }}</p>
+			<Button :href="personalAbsenceSettingsUrl" target="_blank" rel="noopener noreferrer">
+				<template #icon>
+					<OpenInNewIcon :size="20" />
+				</template>
+				{{ t('mail', 'Edit absence settings') }}
+			</Button>
+		</template>
+		<template v-else>
+			<div class="form__multi-row">
+				<fieldset class="form__fieldset">
+					<label for="ooo-first-day">{{ t('mail', 'First day') }}</label>
+					<DatetimePicker
+						id="ooo-first-day"
+						v-model="firstDay"
+						:disabled="!enabled" />
+				</fieldset>
+
+				<fieldset class="form__fieldset">
+					<div class="form__fieldset__label">
+						<input
+							id="ooo-enable-last-day"
+							v-model="enableLastDay"
+							type="checkbox"
+							:disabled="!enabled">
+						<label for="ooo-enable-last-day">
+							{{ t('mail', 'Last day (optional)') }}
+						</label>
+					</div>
+					<DatetimePicker
+						id="ooo-last-day"
+						v-model="lastDay"
+						:disabled="!enabled || !enableLastDay" />
+				</fieldset>
+			</div>
+
 			<fieldset class="form__fieldset">
-				<label for="ooo-first-day">{{ t('mail', 'First day') }}</label>
-				<DatetimePicker
-					id="ooo-first-day"
-					v-model="firstDay"
-					:disabled="!enabled" />
+				<label for="ooo-subject">{{ t('mail', 'Subject') }}</label>
+				<input
+					id="ooo-subject"
+					v-model="subject"
+					type="text"
+					:disabled="followingSystem">
+				<p class="form__fieldset__description">
+					{{ t('mail', '${subject} will be replaced with the subject of the message you are responding to') }}
+				</p>
 			</fieldset>
 
 			<fieldset class="form__fieldset">
-				<div class="form__fieldset__label">
-					<input
-						id="ooo-enable-last-day"
-						v-model="enableLastDay"
-						type="checkbox"
-						:disabled="!enabled">
-					<label for="ooo-enable-last-day">
-						{{ t('mail', 'Last day (optional)') }}
-					</label>
-				</div>
-				<DatetimePicker
-					id="ooo-last-day"
-					v-model="lastDay"
-					:disabled="!enabled || !enableLastDay" />
+				<label for="ooo-message">{{ t('mail', 'Message') }}</label>
+				<TextEditor
+					id="ooo-message"
+					v-model="message"
+					:html="false"
+					:disabled="followingSystem"
+					:bus="{ '$on': () => { /* noop */ } }" />
 			</fieldset>
-		</div>
-
-		<fieldset class="form__fieldset">
-			<label for="ooo-subject">{{ t('mail', 'Subject') }}</label>
-			<input
-				id="ooo-subject"
-				v-model="subject"
-				type="text"
-				:disabled="!enabled">
-			<p class="form__fieldset__description">
-				{{ t('mail', '${subject} will be replaced with the subject of the message you are responding to') }}
-			</p>
-		</fieldset>
-
-		<fieldset class="form__fieldset">
-			<label for="ooo-message">{{ t('mail', 'Message') }}</label>
-			<TextEditor
-				id="ooo-message"
-				v-model="message"
-				:html="false"
-				:disabled="!enabled"
-				:bus="{ '$on': () => { /* noop */ } }" />
-		</fieldset>
+		</template>
 
 		<p v-if="errorMessage">
 			{{ t('mail', 'Oh Snap!') }}
@@ -118,9 +139,15 @@
 import { NcDatetimePicker as DatetimePicker, NcButton as Button } from '@nextcloud/vue'
 import TextEditor from './TextEditor.vue'
 import CheckIcon from 'vue-material-design-icons/Check'
-import { buildOutOfOfficeSieveScript, parseOutOfOfficeState } from '../util/outOfOffice.js'
-import logger from '../logger.js'
 import { html, plain, toHtml, toPlain } from '../util/text.js'
+import { loadState } from '@nextcloud/initial-state'
+import { generateUrl } from '@nextcloud/router'
+import OpenInNewIcon from 'vue-material-design-icons/OpenInNew.vue'
+import * as OutOfOfficeService from '../service/OutOfOfficeService.js'
+
+const OOO_DISABLED = 'disabled'
+const OOO_ENABLED = 'enabled'
+const OOO_FOLLOW_SYSTEM = 'system'
 
 export default {
 	name: 'OutOfOfficeForm',
@@ -129,6 +156,7 @@ export default {
 		TextEditor,
 		Button,
 		CheckIcon,
+		OpenInNewIcon,
 	},
 	props: {
 		account: {
@@ -137,8 +165,14 @@ export default {
 		},
 	},
 	data() {
+		const nextcloudVersion = parseInt(OC.config.version.split('.')[0])
+		const enableSystemOutOfOffice = loadState('mail', 'enable-system-out-of-office', false)
+
 		return {
-			enabled: false,
+			OOO_DISABLED,
+			OOO_ENABLED,
+			OOO_FOLLOW_SYSTEM,
+			enabled: this.account.outOfOfficeFollowsSystem ? OOO_FOLLOW_SYSTEM : OOO_DISABLED,
 			enableLastDay: false,
 			firstDay: new Date(),
 			lastDay: null,
@@ -146,6 +180,8 @@ export default {
 			message: '',
 			loading: false,
 			errorMessage: '',
+			hasPersonalAbsenceSettings: nextcloudVersion >= 28 && enableSystemOutOfOffice,
+			personalAbsenceSettingsUrl: generateUrl('/settings/user/availability'),
 		}
 	},
 	computed: {
@@ -153,6 +189,14 @@ export default {
 		 * @return {boolean}
 		 */
 		valid() {
+			if (this.followingSystem) {
+				return true
+			}
+
+			if (this.enabled === OOO_DISABLED) {
+				return true
+			}
+
 			return !!(this.firstDay
 				&& (!this.enableLastDay || (this.enableLastDay && this.lastDay))
 				&& (!this.enableLastDay || (this.lastDay >= this.firstDay))
@@ -160,30 +204,6 @@ export default {
 				&& this.message)
 		},
 
-		/**
-		 * @return {{script: string, scriptName: string}|undefined}
-		 */
-		sieveScriptData() {
-			return this.$store.getters.getActiveSieveScript(this.account.id)
-		},
-
-		/**
-		 * @return {object|undefined}
-		 */
-		parsedState() {
-			if (!this.sieveScriptData?.script) {
-				return undefined
-			}
-
-			try {
-				return parseOutOfOfficeState(this.sieveScriptData.script).data
-			} catch (error) {
-				logger.warn('Failed to parse OOO state', { error })
-			}
-
-			return undefined
-		},
-
 		/**
 		 * Main address and all aliases formatted for use with sieve.
 		 *
@@ -198,20 +218,15 @@ export default {
 				 ...this.account.aliases,
 			 ].map(({ name, alias }) => `${name} <${alias}>`)
 		},
+
+		/**
+		 * @return {boolean}
+		 */
+		followingSystem() {
+			return this.hasPersonalAbsenceSettings && this.enabled === OOO_FOLLOW_SYSTEM
+		},
 	},
 	watch: {
-		parsedState: {
-			immediate: true,
-			handler(state) {
-				state ??= {}
-				this.enabled = !!state.enabled ?? false
-				this.firstDay = state.start ?? new Date()
-				this.lastDay = state.end ?? null
-				this.enableLastDay = !!this.lastDay
-				this.subject = state.subject ?? ''
-				this.message = toHtml(plain(state.message ?? '')).value
-			},
-		},
 		enableLastDay(enableLastDay) {
 			if (enableLastDay) {
 				this.lastDay = new Date(this.firstDay)
@@ -235,37 +250,61 @@ export default {
 			this.lastDay.setDate(firstDay.getDate() + diffDays)
 		},
 	},
+	async mounted() {
+		await this.fetchState()
+	},
 	methods: {
+		async fetchState() {
+			const { state } = await OutOfOfficeService.fetch(this.account.id)
+
+			if (this.account.outOfOfficeFollowsSystem) {
+				this.enabled = OOO_FOLLOW_SYSTEM
+			} else {
+				this.enabled = state.enabled ? OOO_ENABLED : OOO_DISABLED
+			}
+			if (state.enabled) {
+				this.firstDay = state.start ? new Date(state.start) : new Date()
+				this.lastDay = state.end ? new Date(state.end) : null
+			}
+			this.enableLastDay = !!this.lastDay
+			this.subject = state.subject
+			this.message = toHtml(plain(state.message)).value
+		},
 		async submit() {
 			this.loading = true
 			this.errorMessage = ''
 
-			const state = parseOutOfOfficeState(this.sieveScriptData.script)
-			const originalScript = state.sieveScript
-
-			const enrichedScript = buildOutOfOfficeSieveScript(originalScript, {
-				enabled: this.enabled,
-				start: this.firstDay,
-				end: this.lastDay,
-				subject: this.subject,
-				message: toPlain(html(this.message)).value, // CKEditor always returns html data
-				allowedRecipients: this.aliases,
-			})
-
 			try {
-				await this.$store.dispatch('updateActiveSieveScript', {
-					accountId: this.account.id,
-					scriptData: {
-						...this.sieveScriptData,
-						script: enrichedScript,
-					},
-				})
+				if (this.followingSystem) {
+					await OutOfOfficeService.followSystem(this.account.id)
+					this.$store.commit('patchAccount', {
+						account: this.account,
+						data: {
+							outOfOfficeFollowsSystem: true,
+						},
+					})
+				} else {
+					await OutOfOfficeService.update(this.account.id, {
+						enabled: this.enabled === OOO_ENABLED,
+						start: this.firstDay,
+						end: this.lastDay,
+						subject: this.subject,
+						message: toPlain(html(this.message)).value, // CKEditor always returns html data
+						allowedRecipients: this.aliases,
+					})
+					this.$store.commit('patchAccount', {
+						account: this.account,
+						data: {
+							outOfOfficeFollowsSystem: false,
+						},
+					})
+				}
+				await this.$store.dispatch('fetchActiveSieveScript', { accountId: this.account.id })
 			} catch (error) {
 				this.errorMessage = error.message
 			} finally {
 				this.loading = false
 			}
-
 		},
 	},
 }
diff --git a/src/service/OutOfOfficeService.js b/src/service/OutOfOfficeService.js
new file mode 100644
index 0000000000..023b8f4642
--- /dev/null
+++ b/src/service/OutOfOfficeService.js
@@ -0,0 +1,66 @@
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+import { generateUrl } from '@nextcloud/router'
+import axios from '@nextcloud/axios'
+
+/**
+ * @typedef {{ enabled: bool, start: string, end: string, subject: string, message: string }} OutOfOfficeState
+ */
+
+/**
+ * @typedef {{ state: OutOfOfficeState, script: string, untouchedScript: string }} OutOfOfficeStateResponse
+ */
+
+/**
+ * @param {number} accountId
+ * @return {Promise<OutOfOfficeStateResponse>}
+ */
+export async function fetch(accountId) {
+	const url = generateUrl('/apps/mail/api/out-of-office/{accountId}', { accountId })
+
+	const { data } = await axios.get(url)
+	return data.data
+}
+
+/**
+ * @param {number} accountId
+ * @param {OutOfOfficeState} outOfOfficeState
+ * @return {Promise<OutOfOfficeStateResponse>}
+ */
+export async function update(accountId, outOfOfficeState) {
+	const url = generateUrl('/apps/mail/api/out-of-office/{accountId}', { accountId })
+
+	const { data } = await axios.post(url, outOfOfficeState)
+	return data.data
+}
+
+/**
+ * @param {number} accountId
+ * @return {Promise<OutOfOfficeStateResponse>}
+ */
+export async function followSystem(accountId) {
+	const url = generateUrl('/apps/mail/api/out-of-office/{accountId}/follow-system', { accountId })
+
+	const { data } = await axios.post(url)
+	return data.data
+}
diff --git a/src/tests/unit/util/outOfOffice.spec.js b/src/tests/unit/util/outOfOffice.spec.js
deleted file mode 100644
index 89965168cf..0000000000
--- a/src/tests/unit/util/outOfOffice.spec.js
+++ /dev/null
@@ -1,195 +0,0 @@
-/**
- * @copyright Copyright (c) 2022 Richard Steinmetz <richard@steinmetz.cloud>
- *
- * @author Richard Steinmetz <richard@steinmetz.cloud>
- *
- * @license AGPL-3.0-or-later
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-import {
-	buildOutOfOfficeSieveScript, escapeStringForSieve,
-	formatDateForSieve,
-	parseOutOfOfficeState,
-} from '../../../util/outOfOffice'
-
-describe('outOfOffice', () => {
-	describe('parseOutOfOfficeState', () => {
-		it('should parse a sieve script containing an enabled vacation responder', () => {
-			const script = readTestData('sieve-vacation-on.txt')
-			const cleanedScript = readTestData('sieve-vacation-cleaned.txt')
-			const expected = {
-				sieveScript: cleanedScript,
-				data: {
-					version: 1,
-					enabled: true,
-					start: new Date('2022-09-02'),
-					end: new Date('2022-09-08'),
-					subject: 'On vacation',
-					message: 'I\'m on vacation.',
-				},
-			}
-			const actual = parseOutOfOfficeState(script)
-			expect(actual).toEqual(expected)
-		})
-
-		it('should parse a sieve script containing a disabled vacation responder', () => {
-			const script = readTestData('sieve-vacation-off.txt')
-			const cleanedScript = readTestData('sieve-vacation-cleaned.txt')
-			const expected = {
-				sieveScript: cleanedScript,
-				data: {
-					version: 1,
-					enabled: false,
-					subject: 'On vacation',
-					message: 'I\'m on vacation.',
-				},
-			}
-			const actual = parseOutOfOfficeState(script)
-			expect(actual).toEqual(expected)
-		})
-
-		it('should leave a foreign script untouched', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = {
-				sieveScript: script,
-				data: undefined,
-			}
-			const actual = parseOutOfOfficeState(script)
-			expect(actual).toEqual(expected)
-		})
-	})
-
-	describe('buildOutOfOfficeSieveScript', () => {
-		it('should build a correct sieve script when the vacation responder is enabled', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-on.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: true,
-				start: new Date('2022-09-02'),
-				end: new Date('2022-09-08'),
-				subject: 'On vacation',
-				message: 'I\'m on vacation.',
-				allowedRecipients: [
-					'Test Test <test@test.org>',
-					'Test Alias <alias@test.org>',
-				]
-			})
-			expect(actual).toEqual(expected)
-		})
-
-		it('should build a correct sieve script when the vacation responder is enabled and no end date is given', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-on-no-end-date.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: true,
-				start: new Date('2022-09-02'),
-				subject: 'On vacation',
-				message: 'I\'m on vacation.',
-				allowedRecipients: [
-					'Test Test <test@test.org>',
-					'Test Alias <alias@test.org>',
-				]
-			})
-			expect(actual).toEqual(expected)
-		})
-
-		it('should build a correct sieve script when the vacation responder is enabled and the message contains special chars', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-on-special-chars-message.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: true,
-				start: new Date('2022-09-02'),
-				subject: 'On vacation',
-				message: 'I\'m on vacation.\n"Hello, World!"\n\\ escaped backslash',
-				allowedRecipients: [
-					'Test Test <test@test.org>',
-					'Test Alias <alias@test.org>',
-				]
-			})
-			expect(actual).toEqual(expected)
-		})
-
-		it('should build a correct sieve script when the vacation responder is enabled and the subject contains special chars', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-on-special-chars-subject.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: true,
-				start: new Date('2022-09-02'),
-				subject: 'On vacation, \"Hello, World!\", \\ escaped backslash',
-				message: 'I\'m on vacation.',
-				allowedRecipients: [
-					'Test Test <test@test.org>',
-					'Test Alias <alias@test.org>',
-				]
-			})
-			expect(actual).toEqual(expected)
-		})
-
-		it('should build a correct sieve script when the vacation responder is enabled and a subject placeholder is used', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-on-subject-placeholder.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: true,
-				start: new Date('2022-09-02'),
-				end: new Date('2022-09-08'),
-				subject: 'Re: ${subject}',
-				message: 'I\'m on vacation.',
-				allowedRecipients: [
-					'Test Test <test@test.org>',
-					'Test Alias <alias@test.org>',
-				]
-			})
-			expect(actual).toEqual(expected)
-		})
-
-		it('should build a correct sieve script when the vacation responder is disabled', () => {
-			const script = readTestData('sieve-vacation-cleaned.txt')
-			const expected = readTestData('sieve-vacation-off.txt')
-			const actual = buildOutOfOfficeSieveScript(script, {
-				enabled: false,
-				subject: 'On vacation',
-				message: 'I\'m on vacation.',
-			})
-			expect(actual).toEqual(expected)
-		})
-	})
-
-	describe('formatDateForSieve', () => {
-		it('should format a JS date instance according to YYYY-MM-DD', () => {
-			const date = new Date('2022-09-02')
-			const expected = '2022-09-02'
-			const actual = formatDateForSieve(date)
-			expect(actual).toEqual(expected)
-		})
-	})
-
-	describe('escapeStringForSieve', () => {
-		it('should escape double quotes', () => {
-			const string = 'A string with "quotes"'
-			const expected = 'A string with \\"quotes\\"'
-			const actual = escapeStringForSieve(string)
-			expect(actual).toEqual(expected)
-		})
-
-		it('should escape backslashes', () => {
-			const string = 'A string with \\ backslashes'
-			const expected = 'A string with \\\\ backslashes'
-			const actual = escapeStringForSieve(string)
-			expect(actual).toEqual(expected)
-		})
-	})
-})
diff --git a/src/util/outOfOffice.js b/src/util/outOfOffice.js
deleted file mode 100644
index dc93a17eb1..0000000000
--- a/src/util/outOfOffice.js
+++ /dev/null
@@ -1,213 +0,0 @@
-/**
- * @copyright Copyright (c) 2022 Richard Steinmetz <richard@steinmetz.cloud>
- *
- * @author Richard Steinmetz <richard@steinmetz.cloud>
- *
- * @license AGPL-3.0-or-later
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-const MARKER = '### Nextcloud Mail: Vacation Responder ### DON\'T EDIT ###'
-const DATA_MARKER = '# DATA: '
-const VERSION = 1
-
-// Parser states
-const PARSER_COPY = 0
-const PARSER_SKIP = 1
-
-export class OOOParserError extends Error {}
-
-/**
- * Parse embedded out of office state from the given sieve script.
- * Return the original sieve script without any out of office data/script.
- *
- * @param {string} sieveScript
- * @return {{data: object|undefined, sieveScript: string}}
- */
-export function parseOutOfOfficeState(sieveScript) {
-	const lines = sieveScript.split(/\r?\n/)
-
-	const out = []
-	let data
-
-	let state = PARSER_COPY
-	let nextState = state
-
-	for (const line of lines) {
-		switch (state) {
-		case PARSER_COPY:
-			if (line.startsWith(MARKER)) {
-				nextState = PARSER_SKIP
-				break
-			}
-			out.push(line)
-			break
-		case PARSER_SKIP:
-			if (line.startsWith(MARKER)) {
-				nextState = PARSER_COPY
-			} else if (line.startsWith(DATA_MARKER)) {
-				const json = line.slice(DATA_MARKER.length)
-				data = JSON.parse(json)
-				if (data.start) data.start = new Date(data.start)
-				if (data.end) data.end = new Date(data.end)
-			}
-			break
-		default:
-			throw new OOOParserError('Reached an invalid state')
-		}
-		state = nextState
-	}
-
-	return {
-		sieveScript: out.join('\n'),
-		data,
-	}
-}
-
-/**
- * Embed vacation responder action and out of office state into the given sieve script.
- *
- * @param {string} sieveScript
- * @param {object} data
- * @param {bool} data.enabled
- * @param {Date=} data.start First day (inclusive)
- * @param {Date=} data.end Last day (inclusive)
- * @param {string} data.subject
- * @param {string} data.message
- * @param {string[]=} data.allowedRecipients Only respond if recipient of incoming mail is in this list. Format: `Test Test <test@test.com>`
- * @return {string} Sieve script
- */
-export function buildOutOfOfficeSieveScript(sieveScript, {
-	enabled,
-	start,
-	end,
-	subject,
-	message,
-	allowedRecipients,
-}) {
-	// State to be embedded in the sieve script
-	const data = {
-		version: VERSION,
-		enabled,
-		start: start ? formatDateForSieve(start) : undefined,
-		end: end ? formatDateForSieve(end) : undefined,
-		subject,
-		message,
-	}
-
-	// Save only state if vacation responder is disabled
-	if (!enabled) {
-		delete data.start
-		delete data.end
-		return [
-			sieveScript,
-			MARKER,
-			DATA_MARKER + JSON.stringify(data),
-			MARKER,
-		].join('\n')
-	}
-
-	// Build if condition for start and end dates
-	let condition
-	if (end) {
-		condition = `allof(currentdate :value "ge" "date" "${formatDateForSieve(start)}", currentdate :value "le" "date" "${formatDateForSieve(end)}")`
-	} else {
-		condition = `currentdate :value "ge" "date" "${formatDateForSieve(start)}"`
-	}
-
-	// Build vacation command
-	const vacation = [
-		'vacation',
-		':days 4',
-		`:subject "${escapeStringForSieve(subject)}"`,
-	]
-
-	if (allowedRecipients?.length) {
-		const formattedRecipients = allowedRecipients.map(recipient => `"${recipient}"`).join(', ')
-		vacation.push(`:addresses [${formattedRecipients}]`)
-	}
-
-	vacation.push(`"${escapeStringForSieve(message)}"`)
-
-	// Build sieve script
-	/* eslint-disable no-template-curly-in-string */
-	const subjectSection = [
-		'set "subject" "";',
-		'if header :matches "subject" "*" {',
-		'\tset "subject" "${1}";',
-		'}',
-	]
-	const hasSubjectPlaceholder
-		= subject.indexOf('${subject}') !== -1 || message.indexOf('${subject}') !== -1
-	/* eslint-enable no-template-curly-in-string */
-
-	const requireSection = [
-		MARKER,
-		'require "date";',
-		'require "relational";',
-		'require "vacation";',
-	]
-	if (hasSubjectPlaceholder) {
-		requireSection.push('require "variables";')
-	}
-	requireSection.push(MARKER)
-
-	const vacationSection = [
-		MARKER,
-		DATA_MARKER + JSON.stringify(data),
-	]
-	if (hasSubjectPlaceholder) {
-		vacationSection.push(...subjectSection)
-	}
-	vacationSection.push(
-		`if ${condition} {`,
-		`\t${vacation.join(' ')};`,
-		'}',
-		MARKER,
-	)
-
-	return [
-		...requireSection,
-		sieveScript,
-		...vacationSection,
-	].join('\n')
-}
-
-/**
- * Format a JavaScript date object to use with the sieve :vacation action.
- *
- * @param {Date} date JavaScript date object
- * @return {string} YYYY-MM-DD
- */
-export function formatDateForSieve(date) {
-	const year = date.getFullYear().toString().padStart(4, '0')
-	const month = (date.getMonth() + 1).toString().padStart(2, '0')
-	const day = date.getDate().toString().padStart(2, '0')
-	return `${year}-${month}-${day}`
-}
-
-/**
- * Escape a string for use in a sieve script.
- * The string has to be surrounded by double quotes (`"`) manually.
- *
- * @param {string} string String to escape
- * @return {string} Escaped string
- */
-export function escapeStringForSieve(string) {
-	return string
-		.replaceAll(/\\/g, '\\\\')
-		.replaceAll(/"/g, '\\"')
-}
diff --git a/tests/Integration/Db/MailAccountTest.php b/tests/Integration/Db/MailAccountTest.php
index 7d7fdaaa45..133197b92d 100644
--- a/tests/Integration/Db/MailAccountTest.php
+++ b/tests/Integration/Db/MailAccountTest.php
@@ -48,6 +48,7 @@ public function testToAPI() {
 		$a->setOrder(13);
 		$a->setQuotaPercentage(10);
 		$a->setTrashRetentionDays(60);
+		$a->setOutOfOfficeFollowsSystem(true);
 
 		$this->assertEquals([
 			'id' => 12345,
@@ -80,7 +81,8 @@ public function testToAPI() {
 			'trashRetentionDays' => 60,
 			'junkMailboxId' => null,
 			'snoozeMailboxId' => null,
-			'searchBody' => false
+			'searchBody' => false,
+			'outOfOfficeFollowsSystem' => true,
 		], $a->toJson());
 	}
 
@@ -116,7 +118,8 @@ public function testMailAccountConstruct() {
 			'trashRetentionDays' => 60,
 			'junkMailboxId' => null,
 			'snoozeMailboxId' => null,
-			'searchBody' => false
+			'searchBody' => false,
+			'outOfOfficeFollowsSystem' => false,
 		];
 		$a = new MailAccount($expected);
 		// TODO: fix inconsistency
diff --git a/tests/Unit/Controller/OutOfOfficeControllerTest.php b/tests/Unit/Controller/OutOfOfficeControllerTest.php
new file mode 100644
index 0000000000..0bbd5ba57e
--- /dev/null
+++ b/tests/Unit/Controller/OutOfOfficeControllerTest.php
@@ -0,0 +1,205 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Unit\Controller;
+
+use ChristophWurst\Nextcloud\Testing\ServiceMockObject;
+use ChristophWurst\Nextcloud\Testing\TestCase;
+use DateTimeImmutable;
+use OCA\Mail\Account;
+use OCA\Mail\Controller\OutOfOfficeController;
+use OCA\Mail\Db\MailAccount;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+use OCP\IUser;
+use OCP\User\IAvailabilityCoordinator;
+use OCP\User\IOutOfOfficeData;
+use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Container\ContainerInterface;
+
+class OutOfOfficeControllerTest extends TestCase {
+	private ServiceMockObject $serviceMock;
+	private OutOfOfficeController $outOfOfficeController;
+
+	/** @var ContainerInterface|MockObject */
+	private $container;
+
+	/** @var IAvailabilityCoordinator|MockObject */
+	private $availabilityCoordinator;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		if (!interface_exists(IAvailabilityCoordinator::class)
+		 || !interface_exists(IOutOfOfficeData::class)) {
+			$this->markTestSkipped('Out-of-office feature is not available');
+		}
+
+		$this->container = $this->createMock(ContainerInterface::class);
+		$this->availabilityCoordinator = $this->createMock(IAvailabilityCoordinator::class);
+
+		$this->container->expects(self::once())
+			->method('get')
+			->with(IAvailabilityCoordinator::class)
+			->willReturn($this->availabilityCoordinator);
+
+		$this->serviceMock = $this->createServiceMock(OutOfOfficeController::class, [
+			'userId' => 'user',
+			'container' => $this->container,
+		]);
+		$this->outOfOfficeController = $this->serviceMock->getService();
+	}
+
+	private function createOutOfOfficeData(
+		string $id,
+		IUser $user,
+		int $startDate,
+		int $endDate,
+		string $subject,
+		string $message,
+	): ?IOutOfOfficeData {
+		if (!interface_exists(IOutOfOfficeData::class)) {
+			return null;
+		}
+
+		$data = $this->createMock(IOutOfOfficeData::class);
+		$data->method('getId')->willReturn($id);
+		$data->method('getUser')->willReturn($user);
+		$data->method('getStartDate')->willReturn($startDate);
+		$data->method('getEndDate')->willReturn($endDate);
+		$data->method('getShortMessage')->willReturn($subject);
+		$data->method('getMessage')->willReturn($message);
+		return $data;
+	}
+
+
+	public function disabledOutOfOfficeDataProvider(): array {
+		$user = $this->createMock(IUser::class);
+		return [
+			[null],
+			[$this->createOutOfOfficeData('2', $user, 0, 1, '', '')],
+			[$this->createOutOfOfficeData('2', $user, PHP_INT_MAX - 1, PHP_INT_MAX, '', '')],
+			[$this->createOutOfOfficeData('2', $user, 0, 1500, 'Subject', 'Message')],
+		];
+	}
+
+	/**
+	 * @dataProvider disabledOutOfOfficeDataProvider
+	 */
+	public function testFollowSystemWithDisabledOutOfOffice(?IOutOfOfficeData $data): void {
+		$user = $this->createMock(IUser::class);
+
+		$mailAccount = new MailAccount();
+		$mailAccount->setId(1);
+		$mailAccount->setOutOfOfficeFollowsSystem(false);
+		$account = new Account($mailAccount);
+
+		$userSession = $this->serviceMock->getParameter('userSession');
+		$userSession->expects(self::once())
+			->method('getUser')
+			->willReturn($user);
+		$accountService = $this->serviceMock->getParameter('accountService');
+		$accountService->expects(self::once())
+			->method('findById')
+			->with(1)
+			->willReturn($account);
+		$timeFactory = $this->serviceMock->getParameter('timeFactory');
+		$timeFactory->expects(self::once())
+			->method('getTime')
+			->willReturn(1500);
+		$this->availabilityCoordinator->expects(self::once())
+			->method('getCurrentOutOfOfficeData')
+			->with($user)
+			->willReturn($data);
+		$outOfOfficeService = $this->serviceMock->getParameter('outOfOfficeService');
+		$outOfOfficeService->expects(self::once())
+			->method('disable')
+			->with($mailAccount);
+		$outOfOfficeService->expects(self::never())
+			->method('update');
+
+		$this->outOfOfficeController->followSystem(1);
+
+		self::assertTrue($mailAccount->getOutOfOfficeFollowsSystem());
+	}
+
+	public function enabledOutOfOfficeDataProvider(): array {
+		$user = $this->createMock(IUser::class);
+		return [
+			[$this->createOutOfOfficeData('2', $user, 1000, 2000, 'Subject', 'Message')],
+			[$this->createOutOfOfficeData('2', $user, 1500, 2000, 'Subject', 'Message')],
+		];
+	}
+
+	/**
+	 * @dataProvider enabledOutOfOfficeDataProvider
+	 */
+	public function testFollowSystemWithEnabledOutOfOffice(?IOutOfOfficeData $data): void {
+		$startDate = $data->getStartDate();
+		$endDate = $data->getEndDate();
+
+		$user = $this->createMock(IUser::class);
+
+		$mailAccount = new MailAccount();
+		$mailAccount->setId(1);
+		$mailAccount->setOutOfOfficeFollowsSystem(false);
+		$account = new Account($mailAccount);
+
+		$userSession = $this->serviceMock->getParameter('userSession');
+		$userSession->expects(self::once())
+			->method('getUser')
+			->willReturn($user);
+		$accountService = $this->serviceMock->getParameter('accountService');
+		$accountService->expects(self::once())
+			->method('findById')
+			->with(1)
+			->willReturn($account);
+		$timeFactory = $this->serviceMock->getParameter('timeFactory');
+		$timeFactory->expects(self::once())
+			->method('getTime')
+			->willReturn(1500);
+		$this->availabilityCoordinator->expects(self::once())
+			->method('getCurrentOutOfOfficeData')
+			->with($user)
+			->willReturn($data);
+		$outOfOfficeService = $this->serviceMock->getParameter('outOfOfficeService');
+		$outOfOfficeService->expects(self::never())
+			->method('disable');
+		$outOfOfficeService->expects(self::once())
+			->method('update')
+			->with($mailAccount, self::callback(function (OutOfOfficeState $state) use ($endDate, $startDate): bool {
+				self::assertTrue($state->isEnabled());
+				self::assertEquals(new DateTimeImmutable("@$startDate"), $state->getStart());
+				self::assertEquals(new DateTimeImmutable("@$endDate"), $state->getEnd());
+				self::assertEquals('Subject', $state->getSubject());
+				self::assertEquals('Message', $state->getMessage());
+				return true;
+			}));
+
+		$this->outOfOfficeController->followSystem(1);
+
+		self::assertTrue($mailAccount->getOutOfOfficeFollowsSystem());
+	}
+}
diff --git a/tests/Unit/Controller/PageControllerTest.php b/tests/Unit/Controller/PageControllerTest.php
index 937559f109..5bd1acf1f0 100644
--- a/tests/Unit/Controller/PageControllerTest.php
+++ b/tests/Unit/Controller/PageControllerTest.php
@@ -50,6 +50,7 @@
 use OCP\IUserManager;
 use OCP\IUserSession;
 use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
 
 class PageControllerTest extends TestCase {
@@ -112,6 +113,9 @@ class PageControllerTest extends TestCase {
 
 	private SmimeService $smimeService;
 
+	/** @var ContainerInterface|MockObject */
+	private $container;
+
 	protected function setUp(): void {
 		parent::setUp();
 
@@ -134,6 +138,7 @@ protected function setUp(): void {
 		$this->credentialStore = $this->createMock(ICredentialStore::class);
 		$this->smimeService = $this->createMock(SmimeService::class);
 		$this->userManager = $this->createMock(IUserManager::class);
+		$this->container = $this->createMock(ContainerInterface::class);
 
 		$this->controller = new PageController(
 			$this->appName,
@@ -155,6 +160,7 @@ protected function setUp(): void {
 			$this->smimeService,
 			$this->aiIntegrationsService,
 			$this->userManager,
+			$this->container,
 		);
 	}
 
diff --git a/tests/Unit/Controller/SieveControllerTest.php b/tests/Unit/Controller/SieveControllerTest.php
index eec9f238fc..2f3c5693d9 100644
--- a/tests/Unit/Controller/SieveControllerTest.php
+++ b/tests/Unit/Controller/SieveControllerTest.php
@@ -4,6 +4,7 @@
 
 /**
  * @author Daniel Kesselberg <mail@danielkesselberg.de>
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
  *
  * Mail
  *
@@ -25,11 +26,10 @@
 
 use ChristophWurst\Nextcloud\Testing\ServiceMockObject;
 use Horde\ManageSieve\Exception;
-use OCA\Mail\Account;
 use OCA\Mail\Controller\SieveController;
 use OCA\Mail\Db\MailAccount;
-use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Exception\CouldNotConnectException;
+use OCA\Mail\Sieve\NamedSieveScript;
 use OCA\Mail\Tests\Integration\TestCase;
 use OCP\Security\IRemoteHostValidator;
 use PHPUnit\Framework\MockObject\MockObject;
@@ -129,56 +129,23 @@ public function testUpdateAccountEnableNoConnection(): void {
 	}
 
 	public function testGetActiveScript(): void {
-		$mailAccount = new MailAccount();
-		$mailAccount->setSieveEnabled(true);
-		$mailAccount->setSieveHost('localhost');
-		$mailAccount->setSievePort(4190);
-		$mailAccount->setSieveUser('user');
-		$mailAccount->setSievePassword('password');
-		$mailAccount->setSieveSslMode('');
-
-		$accountService = $this->serviceMock->getParameter('accountService');
-		$accountService->expects($this->once())
-			->method('find')
+		$sieveService = $this->serviceMock->getParameter('sieveService');
+		$sieveService->expects($this->once())
+			->method('getActiveScript')
 			->with('1', 2)
-			->willReturn(new Account($mailAccount));
+			->willReturn(new NamedSieveScript('nextcloud', '# foo bar'));
 
 		$response = $this->sieveController->getActiveScript(2);
 
 		$this->assertEquals(200, $response->getStatus());
-		$this->assertEquals(['scriptName' => '', 'script' => ''], $response->getData());
-	}
-
-	public function testGetActiveScriptNoSieve(): void {
-		$this->expectException(ClientException::class);
-		$this->expectExceptionMessage('ManageSieve is disabled');
-
-		$mailAccount = new MailAccount();
-		$mailAccount->setSieveEnabled(false);
-
-		$accountService = $this->serviceMock->getParameter('accountService');
-		$accountService->expects($this->once())
-			->method('find')
-			->with('1', 2)
-			->willReturn(new Account($mailAccount));
-
-		$this->sieveController->getActiveScript(2);
+		$this->assertEquals(['scriptName' => 'nextcloud', 'script' => '# foo bar'], $response->getData());
 	}
 
 	public function testUpdateActiveScript(): void {
-		$mailAccount = new MailAccount();
-		$mailAccount->setSieveEnabled(true);
-		$mailAccount->setSieveHost('localhost');
-		$mailAccount->setSievePort(4190);
-		$mailAccount->setSieveUser('user');
-		$mailAccount->setSievePassword('password');
-		$mailAccount->setSieveSslMode('');
-
-		$accountService = $this->serviceMock->getParameter('accountService');
-		$accountService->expects($this->once())
-			->method('find')
-			->with('1', 2)
-			->willReturn(new Account($mailAccount));
+		$sieveService = $this->serviceMock->getParameter('sieveService');
+		$sieveService->expects($this->once())
+			->method('updateActiveScript')
+			->with('1', 2, 'sieve script');
 
 		$response = $this->sieveController->updateActiveScript(2, 'sieve script');
 
diff --git a/tests/Unit/Service/OutOfOffice/OutOfOfficeParserTest.php b/tests/Unit/Service/OutOfOffice/OutOfOfficeParserTest.php
new file mode 100644
index 0000000000..98a2f05ba4
--- /dev/null
+++ b/tests/Unit/Service/OutOfOffice/OutOfOfficeParserTest.php
@@ -0,0 +1,189 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Unit\Service\OutOfOffice;
+
+use ChristophWurst\Nextcloud\Testing\TestCase;
+use DateTimeImmutable;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeParser;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+
+class OutOfOfficeParserTest extends TestCase {
+	private OutOfOfficeParser $outOfOfficeParser;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->outOfOfficeParser = new OutOfOfficeParser();
+	}
+
+	public function testParseEnabledResponder(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on.txt");
+		$cleanedScript = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+
+		$actual = $this->outOfOfficeParser->parseOutOfOfficeState($script);
+		self::assertEquals($script, $actual->getSieveScript());
+		self::assertEquals($cleanedScript, $actual->getUntouchedSieveScript());
+		self::assertEquals(1, $actual->getState()->getVersion());
+		self::assertEquals(true, $actual->getState()->isEnabled());
+		self::assertEquals(new DateTimeImmutable("2022-09-02"), $actual->getState()->getStart());
+		self::assertEquals(new DateTimeImmutable("2022-09-08"), $actual->getState()->getEnd());
+		self::assertEquals("On vacation", $actual->getState()->getSubject());
+		self::assertEquals("I'm on vacation.", $actual->getState()->getMessage());
+	}
+
+	public function testParseDisabledResponder(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-off.txt");
+		$cleanedScript = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+
+		$actual = $this->outOfOfficeParser->parseOutOfOfficeState($script);
+		self::assertEquals($script, $actual->getSieveScript());
+		self::assertEquals($cleanedScript, $actual->getUntouchedSieveScript());
+		self::assertEquals(1, $actual->getState()->getVersion());
+		self::assertEquals(false, $actual->getState()->isEnabled());
+		self::assertEquals(null, $actual->getState()->getStart());
+		self::assertEquals(null, $actual->getState()->getEnd());
+		self::assertEquals("On vacation", $actual->getState()->getSubject());
+		self::assertEquals("I'm on vacation.", $actual->getState()->getMessage());
+	}
+
+	public function testParseLeaveForeignScriptUntouched(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+
+		$actual = $this->outOfOfficeParser->parseOutOfOfficeState($script);
+		self::assertEquals($script, $actual->getSieveScript());
+		self::assertEquals($script, $actual->getUntouchedSieveScript());
+		self::assertEquals(null, $actual->getState());
+	}
+
+	public function testBuildEnabledResponder(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("2022-09-02"),
+				new DateTimeImmutable("2022-09-08"),
+				"On vacation",
+				"I'm on vacation.",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+
+	public function testBuildEnabledResponderWithoutEndDate(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on-no-end-date.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("2022-09-02"),
+				null,
+				"On vacation",
+				"I'm on vacation.",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+
+	public function testBuildEnabledResponderWithSpecialCharsInMessage(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on-special-chars-message.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("2022-09-02"),
+				null,
+				"On vacation",
+				"I'm on vacation.\n\"Hello, World!\"\n\\ escaped backslash",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+
+	public function testBuildEnabledResponderWithSpecialCharsInSubject(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on-special-chars-subject.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("2022-09-02"),
+				null,
+				"On vacation, \"Hello, World!\", \\ escaped backslash",
+				"I'm on vacation.",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+
+	public function testBuildEnabledResponderWithSubjectPlaceholder(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-on-subject-placeholder.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				true,
+				new DateTimeImmutable("2022-09-02"),
+				new DateTimeImmutable("2022-09-08"),
+				'Re: ${subject}',
+				"I'm on vacation.",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+
+	public function testBuildDisabledResponder(): void {
+		$script = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-cleaned.txt");
+		$expected = file_get_contents(__DIR__ . "/../../../data/sieve-vacation-off.txt");
+
+		$actual = $this->outOfOfficeParser->buildSieveScript(
+			new OutOfOfficeState(
+				false,
+				null,
+				null,
+				"On vacation",
+				"I'm on vacation.",
+			),
+			$script,
+			["Test Test <test@test.org>", "Test Alias <alias@test.org>"],
+		);
+		self::assertEquals($expected, $actual);
+	}
+}
diff --git a/tests/Unit/Service/SieveServiceTest.php b/tests/Unit/Service/SieveServiceTest.php
new file mode 100644
index 0000000000..4dba30495c
--- /dev/null
+++ b/tests/Unit/Service/SieveServiceTest.php
@@ -0,0 +1,258 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2023 Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @author Richard Steinmetz <richard@steinmetz.cloud>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Unit\Service;
+
+use ChristophWurst\Nextcloud\Testing\TestCase;
+use OCA\Mail\Account;
+use OCA\Mail\Db\MailAccount;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\SieveService;
+use OCA\Mail\Sieve\SieveClientFactory;
+use PHPUnit\Framework\MockObject\MockObject;
+
+class SieveServiceTest extends TestCase {
+	private SieveService $sieveService;
+
+	/** @var SieveClientFactory|MockObject */
+	private $sieveClientFactory;
+
+	/** @var AccountService|MockObject */
+	private $accountService;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->sieveClientFactory = $this->createMock(SieveClientFactory::class);
+		$this->accountService = $this->createMock(AccountService::class);
+
+		$this->sieveService = new SieveService(
+			$this->sieveClientFactory,
+			$this->accountService,
+		);
+	}
+
+	public function testGetActiveScript(): void {
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost('localhost');
+		$mailAccount->setSievePort(4190);
+		$mailAccount->setSieveUser('user');
+		$mailAccount->setSievePassword('password');
+		$mailAccount->setSieveSslMode('');
+		$account = new Account($mailAccount);
+
+		$client = $this->createMock(\Horde\ManageSieve::class);
+		$client->expects(self::once())
+			->method('getActive')
+			->willReturn('nextcloud');
+		$client->expects(self::once())
+			->method('getScript')
+			->with('nextcloud')
+			->willReturn('# foo bar');
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn($account);
+		$this->sieveClientFactory->expects(self::once())
+			->method('getClient')
+			->with($account)
+			->willReturn($client);
+
+		$actual = $this->sieveService->getActiveScript('1', 2);
+		$this->assertEquals('nextcloud', $actual->getName());
+		$this->assertEquals('# foo bar', $actual->getScript());
+	}
+
+	public function testGetActiveScriptNoName(): void {
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost('localhost');
+		$mailAccount->setSievePort(4190);
+		$mailAccount->setSieveUser('user');
+		$mailAccount->setSievePassword('password');
+		$mailAccount->setSieveSslMode('');
+		$account = new Account($mailAccount);
+
+		$client = $this->createMock(\Horde\ManageSieve::class);
+		$client->expects(self::once())
+			->method('getActive')
+			->willReturn(null);
+		$client->expects(self::never())
+			->method('getScript');
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn($account);
+		$this->sieveClientFactory->expects(self::once())
+			->method('getClient')
+			->with($account)
+			->willReturn($client);
+
+		$actual = $this->sieveService->getActiveScript('1', 2);
+		$this->assertEquals('', $actual->getName());
+		$this->assertEquals('', $actual->getScript());
+	}
+
+	public function scriptTrimDataProvider(): array {
+		return [
+			["# foo bar", "# foo bar"],
+			["# foo bar\r\n", "# foo bar"],
+			["# foo bar\r\n\r\n", "# foo bar"],
+			["\r\n# foo bar", "\r\n# foo bar"],
+			["# foo bar  ", "# foo bar  "],
+		];
+	}
+
+	/**
+	 * @dataProvider scriptTrimDataProvider
+	 */
+	public function testGetActiveScriptTrimsTrailingLineFeeds(string $script, string $expected): void {
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost('localhost');
+		$mailAccount->setSievePort(4190);
+		$mailAccount->setSieveUser('user');
+		$mailAccount->setSievePassword('password');
+		$mailAccount->setSieveSslMode('');
+		$account = new Account($mailAccount);
+
+		$client = $this->createMock(\Horde\ManageSieve::class);
+		$client->expects(self::once())
+			->method('getActive')
+			->willReturn('nextcloud');
+		$client->expects(self::once())
+			->method('getScript')
+			->with('nextcloud')
+			->willReturn($script);
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn($account);
+		$this->sieveClientFactory->expects(self::once())
+			->method('getClient')
+			->with($account)
+			->willReturn($client);
+
+		$actual = $this->sieveService->getActiveScript('1', 2);
+		$this->assertEquals('nextcloud', $actual->getName());
+		$this->assertEquals($expected, $actual->getScript());
+	}
+
+	public function testGetActiveScriptNoSieve(): void {
+		$this->expectException(ClientException::class);
+		$this->expectExceptionMessage('ManageSieve is disabled');
+
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(false);
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn(new Account($mailAccount));
+
+		$this->sieveService->getActiveScript('1', 2);
+	}
+
+	public function testUpdateActiveScript(): void {
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost('localhost');
+		$mailAccount->setSievePort(4190);
+		$mailAccount->setSieveUser('user');
+		$mailAccount->setSievePassword('password');
+		$mailAccount->setSieveSslMode('');
+		$account = new Account($mailAccount);
+
+		$client = $this->createMock(\Horde\ManageSieve::class);
+		$client->expects(self::once())
+			->method('getActive')
+			->willReturn('nextcloud');
+		$client->expects(self::once())
+			->method('installScript')
+			->with('nextcloud', '# foo bar', true);
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn($account);
+		$this->sieveClientFactory->expects(self::once())
+			->method('getClient')
+			->with($account)
+			->willReturn($client);
+
+		$this->sieveService->updateActiveScript('1', 2, '# foo bar');
+	}
+
+	public function testUpdateActiveScriptWithNoName(): void {
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(true);
+		$mailAccount->setSieveHost('localhost');
+		$mailAccount->setSievePort(4190);
+		$mailAccount->setSieveUser('user');
+		$mailAccount->setSievePassword('password');
+		$mailAccount->setSieveSslMode('');
+		$account = new Account($mailAccount);
+
+		$client = $this->createMock(\Horde\ManageSieve::class);
+		$client->expects(self::once())
+			->method('getActive')
+			->willReturn(null);
+		$client->expects(self::once())
+			->method('installScript')
+			->with('nextcloud', '# foo bar', true);
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn($account);
+		$this->sieveClientFactory->expects(self::once())
+			->method('getClient')
+			->with($account)
+			->willReturn($client);
+
+		$this->sieveService->updateActiveScript('1', 2, '# foo bar');
+	}
+
+	public function testUpdateActiveScriptNoSieve(): void {
+		$this->expectException(ClientException::class);
+		$this->expectExceptionMessage('ManageSieve is disabled');
+
+		$mailAccount = new MailAccount();
+		$mailAccount->setSieveEnabled(false);
+
+		$this->accountService->expects(self::once())
+			->method('find')
+			->with('1', 2)
+			->willReturn(new Account($mailAccount));
+
+		$this->sieveService->updateActiveScript('1', 2, '# foo bar');
+	}
+}
diff --git a/src/tests/data/sieve-vacation-cleaned.txt b/tests/data/sieve-vacation-cleaned.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-cleaned.txt
rename to tests/data/sieve-vacation-cleaned.txt
diff --git a/src/tests/data/sieve-vacation-off.txt b/tests/data/sieve-vacation-off.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-off.txt
rename to tests/data/sieve-vacation-off.txt
diff --git a/src/tests/data/sieve-vacation-on-no-end-date.txt b/tests/data/sieve-vacation-on-no-end-date.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-on-no-end-date.txt
rename to tests/data/sieve-vacation-on-no-end-date.txt
diff --git a/src/tests/data/sieve-vacation-on-special-chars-message.txt b/tests/data/sieve-vacation-on-special-chars-message.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-on-special-chars-message.txt
rename to tests/data/sieve-vacation-on-special-chars-message.txt
diff --git a/src/tests/data/sieve-vacation-on-special-chars-subject.txt b/tests/data/sieve-vacation-on-special-chars-subject.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-on-special-chars-subject.txt
rename to tests/data/sieve-vacation-on-special-chars-subject.txt
diff --git a/src/tests/data/sieve-vacation-on-subject-placeholder.txt b/tests/data/sieve-vacation-on-subject-placeholder.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-on-subject-placeholder.txt
rename to tests/data/sieve-vacation-on-subject-placeholder.txt
diff --git a/src/tests/data/sieve-vacation-on.txt b/tests/data/sieve-vacation-on.txt
similarity index 100%
rename from src/tests/data/sieve-vacation-on.txt
rename to tests/data/sieve-vacation-on.txt
diff --git a/tests/psalm-baseline.xml b/tests/psalm-baseline.xml
index f39a3adb99..d306724e2c 100644
--- a/tests/psalm-baseline.xml
+++ b/tests/psalm-baseline.xml
@@ -1,6 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <files psalm-version="5.14.1@b9d355e0829c397b9b3b47d0c0ed042a8a70284d">
   <file src="lib/AppInfo/Application.php">
+    <InvalidArgument>
+      <code>OutOfOfficeListener::class</code>
+      <code>OutOfOfficeListener::class</code>
+    </InvalidArgument>
     <MissingDependency>
       <code>FilteringProvider</code>
       <code>ImportantMailWidgetV2</code>
@@ -38,4 +42,16 @@
       <code>MailWidgetV2</code>
     </MissingDependency>
   </file>
+  <file src="lib/Listener/OutOfOfficeListener.php">
+    <InvalidTemplateParam>
+      <code>IEventListener</code>
+    </InvalidTemplateParam>
+    <MoreSpecificImplementedParamType>
+      <code>$event</code>
+    </MoreSpecificImplementedParamType>
+    <UndefinedDocblockClass>
+      <code>OutOfOfficeListener</code>
+      <code>OutOfOfficeListener</code>
+    </UndefinedDocblockClass>
+  </file>
 </files>