diff --git a/src/middlewared/middlewared/plugins/mail.py b/src/middlewared/middlewared/plugins/mail.py
index e09be97ad0d0..8ec96feb7c65 100644
--- a/src/middlewared/middlewared/plugins/mail.py
+++ b/src/middlewared/middlewared/plugins/mail.py
@@ -28,13 +28,15 @@ class DenyNetworkActivity(Exception):
     pass
 
 
-class QueueItem:
+class QueueItem(object):
+
     def __init__(self, message):
         self.attempts = 0
         self.message = message
 
 
-class MailQueue:
+class MailQueue(object):
+
     MAX_ATTEMPTS = 3
     MAX_QUEUE_LIMIT = 20
 
@@ -71,7 +73,10 @@ class MailModel(sa.Model):
 
 
 class MailService(ConfigService):
+
     mail_queue = MailQueue()
+    oauth_access_token = None
+    oauth_access_token_expires_at = None
 
     class Config:
         datastore = 'system.email'
@@ -91,7 +96,6 @@ class Config:
         Password('pass', null=True, required=True),
         Dict(
             'oauth',
-            Str('provider'),
             Str('client_id'),
             Str('client_secret'),
             Password('refresh_token'),
@@ -115,7 +119,6 @@ async def mail_extend(self, cfg):
             (
                 'replace', Dict(
                     'oauth',
-                    Str('provider'),
                     Str('client_id', required=True),
                     Str('client_secret', required=True),
                     Password('refresh_token', required=True),
@@ -367,7 +370,7 @@ def read_json():
                 msg[key] = val
 
         try:
-            if config['oauth'] and config['oauth']['provider'] == 'gmail':
+            if config['oauth']:
                 self.middleware.call_sync('mail.gmail_send', msg, config)
             else:
                 server = self._get_smtp_server(config, message['timeout'], local_hostname=local_hostname)
@@ -426,9 +429,7 @@ def _get_smtp_server(self, config, timeout=300, local_hostname=None):
                 local_hostname=local_hostname)
             if config['security'] == 'TLS':
                 server.starttls()
-        if config['oauth'] and config['oauth']['provider'] == 'outlook':
-            self.middleware.call_sync('mail.outlook_xoauth2', server, config)
-        elif config['smtp']:
+        if config['smtp']:
             server.login(config['user'], config['pass'])
 
         return server
@@ -440,7 +441,7 @@ def send_mail_queue(self):
             for queue in list(mq.queue):
                 try:
                     config = self.middleware.call_sync('mail.config')
-                    if config['oauth'] and config['oauth']['provider'] == 'gmail':
+                    if config['oauth']:
                         self.middleware.call_sync('mail.gmail_send', queue.message, config)
                     else:
                         server = self._get_smtp_server(config)
diff --git a/src/middlewared/middlewared/plugins/mail_/gmail.py b/src/middlewared/middlewared/plugins/mail_/gmail.py
index 549fccf26000..e211742fe454 100644
--- a/src/middlewared/middlewared/plugins/mail_/gmail.py
+++ b/src/middlewared/middlewared/plugins/mail_/gmail.py
@@ -59,7 +59,7 @@ def gmail_initialize(self):
 
     @private
     def gmail_build_service(self, config):
-        if config["oauth"] and config["oauth"]["provider"] == "gmail":
+        if config["oauth"]:
             return GmailService(config)
 
         return None
diff --git a/src/middlewared/middlewared/plugins/mail_/outlook.py b/src/middlewared/middlewared/plugins/mail_/outlook.py
deleted file mode 100644
index 40c97e951c9a..000000000000
--- a/src/middlewared/middlewared/plugins/mail_/outlook.py
+++ /dev/null
@@ -1,67 +0,0 @@
-import base64
-from dataclasses import dataclass
-from smtplib import SMTP
-import time
-
-import requests
-
-from middlewared.service import CallError, private, Service
-
-
-@dataclass
-class OutlookToken:
-    token: str
-    expires_at: float
-
-
-class MailService(Service):
-    outlook_tokens: dict[str, OutlookToken] = {}
-
-    @private
-    def outlook_xoauth2(self, server: SMTP, config: dict):
-        server.ehlo()
-
-        if token := self._get_outlook_token(config["fromemail"], config["oauth"]["refresh_token"]):
-            code, response = self._do_xoauth2(server, config["fromemail"], token)
-            if 200 <= code <= 299:
-                return
-
-            self.logger.warning("Outlook XOAUTH2 failed: %r %r. Refreshing access token", code, response)
-
-        self.logger.debug("Requesting Outlook access token")
-        r = requests.post(
-            "https://login.microsoftonline.com/common/oauth2/v2.0/token",
-            data={
-                "grant_type": "refresh_token",
-                "client_id": config["oauth"]["client_id"],
-                "client_secret": config["oauth"]["client_secret"],
-                "refresh_token": config["oauth"]["refresh_token"],
-                "scope": "https://outlook.office.com/SMTP.Send openid offline_access",
-            }
-        )
-        r.raise_for_status()
-        response = r.json()
-
-        token = response["access_token"]
-        self._set_outlook_token(config["fromemail"], config["oauth"]["refresh_token"], token, response["expires_in"])
-
-        code, response = self._do_xoauth2(server, config["fromemail"], token)
-        if 200 <= code <= 299:
-            return
-
-        raise CallError("Outlook XOAUTH2 failed: %r %r" % (code, response))
-
-    def _get_outlook_token(self, email: str, refresh_token: str) -> str | None:
-        for key, token in list(self.outlook_tokens.items()):
-            if token.expires_at < time.monotonic() - 5:
-                self.outlook_tokens.pop(key)
-
-        if token := self.outlook_tokens.get(email + refresh_token):
-            return token.token
-
-    def _set_outlook_token(self, email: str, refresh_token: str, token: str, expires_in: int):
-        self.outlook_tokens[email + refresh_token] = OutlookToken(token, time.monotonic() + expires_in)
-
-    def _do_xoauth2(self, server: SMTP, email: str, access_token: str):
-        auth_string = f"user={email}\1auth=Bearer {access_token}\1\1"
-        return server.docmd("AUTH XOAUTH2", base64.b64encode(auth_string.encode()).decode())