diff --git a/CRM/Mailingtools/Form/Settings.php b/CRM/Mailingtools/Form/Settings.php
index 533a815..adb1f70 100644
--- a/CRM/Mailingtools/Form/Settings.php
+++ b/CRM/Mailingtools/Form/Settings.php
@@ -21,6 +21,7 @@
  * @see https://wiki.civicrm.org/confluence/display/CRMDOC/QuickForm+Reference
  */
 class CRM_Mailingtools_Form_Settings extends CRM_Core_Form {
+
   public function buildQuickForm() {
 
     $config = CRM_Mailingtools_Config::singleton();
@@ -130,7 +131,37 @@ public function buildQuickForm() {
         E::ts('Fix {contact.hash} Token')
     );
 
-    // Token Tools
+    // Regex Tokens
+    $token_indices = range(0,CRM_Mailingtools_RegexToken::MT_REGEX_TOKEN_COUNT);
+    $this->assign('regex_token_indices', $token_indices);
+    foreach ($token_indices as $token_index) {
+      $this->add(
+          'text',
+          "regex_token_{$token_index}_def",
+          E::ts('Regular Expression')
+      );
+      $this->add(
+          'select',
+          "regex_token_{$token_index}_op",
+          E::ts('Operator Type')
+      );
+      $this->add(
+          'text',
+          "regex_token_{$token_index}_val",
+          E::ts('Value Function')
+      );
+    }
+    // set defaults
+    $current_tokens = CRM_Mailingtools_RegexToken::getTokenDefinitions();
+    foreach ($current_tokens as $token_index => $token_definition) {
+      $this->setDefaults([
+          "regex_token_{$token_index}_def" => $token_definition['def'],
+          "regex_token_{$token_index}_op"  => $token_definition['op'],
+          "regex_token_{$token_index}_val" => $token_definition['val'],
+      ]);
+    }
+
+    // Mosaico Save Message
     $this->add(
       'checkbox',
       'mosaico_save_message',
diff --git a/CRM/Mailingtools/RegexToken.php b/CRM/Mailingtools/RegexToken.php
new file mode 100644
index 0000000..bbe7c58
--- /dev/null
+++ b/CRM/Mailingtools/RegexToken.php
@@ -0,0 +1,143 @@
+<?php
+/*-------------------------------------------------------+
+| SYSTOPIA Mailingtools Extension                        |
+| Copyright (C) 2020 SYSTOPIA                            |
+| Author: B. Endres (endres@systopia.de)               |
++--------------------------------------------------------+
+| This program is released as free software under the    |
+| Affero GPL license. You can redistribute it and/or     |
+| modify it under the terms of this license which you    |
+| can read by viewing the included agpl.txt or online    |
+| at www.gnu.org/licenses/agpl.html. Removal of this     |
+| copyright header is strictly prohibited without        |
+| written permission from the original author(s).        |
++--------------------------------------------------------*/
+
+
+use CRM_Mailingtools_ExtensionUtil as E;
+
+/**
+ * Class CRM_Mailingtools_EmailVerifier
+ */
+class CRM_Mailingtools_RegexToken {
+
+  /**
+   * Maximum amount of regex token definitions
+   */
+  const MT_REGEX_TOKEN_COUNT  = 10;
+  const REGEX_DELIMITER  = '#';
+  const OPERATOR_API3    = 'api3';     // API3 call
+  const OPERATOR_STATIC  = 'static';   // static function call
+  const OPERATOR_REPLACE = 'replace';  // preg_replace call
+
+  const VALUE_STATIC_FUNCTION = '/^(?P<class>[a-zA-Z_]+)::(?P<function>[a-zA-Z_]+)$/';
+  const VALUE_API_CALL        = '/^(?P<entity>[a-zA-Z]+)[.](?P<action>[a-zA-Z_]+)$/';
+
+
+  /**
+   * Get the current token definition specs as an array of
+   * [
+   *  'def' => (string) regular expression without delimiters
+   *  'op'  => (string) operator type (api3, static, replace)
+   *  'val' => (string) call spec, e.g. "entity.action", or "class::function"
+   * ]
+   * @return array list of such specs
+   */
+  public static function getTokenDefinitions() {
+    $value = Civi::settings()->get('mailingtools_regex_tokens');
+    if (empty($value) || !is_array($value)) {
+      return [];
+    } else {
+      return $value;
+    }
+  }
+
+  /**
+   * Set the current token definition specs
+   * @param $token_definitions array see getTokenDefinitions
+   */
+  public static function setTokenDefinitions($token_definitions) {
+    Civi::settings()->set('mailingtools_regex_tokens', $token_definitions);
+  }
+
+
+  /**
+   * Verify the presented token definition, and return an
+   *  error string if not valid
+   *
+   * @param $token_definition array definition, see getTokenDefinitions
+   * @return string|false error or false ("all clear")
+   */
+  public static function verifyTokenDefinition($token_definition) {
+    // test if present
+    if (empty($token_definition['def'])) {
+      return E::ts("Incomplete definition: definition (regular expression) missing");
+    }
+    if (empty($token_definition['op'])) {
+      return E::ts("Incomplete definition: value type missing");
+    }
+    if (empty($token_definition['val'])) {
+      return E::ts("Incomplete definition: value missing");
+    }
+
+    // verify definition (regex)
+    try {
+      preg_match(self::REGEX_DELIMITER . $token_definition['def'] . self::REGEX_DELIMITER, 'doesntmatter');
+    } catch (Exception $ex) {
+      return E::ts("Incomplete definition: definition is not a valid regular expression");
+    }
+
+    // verify operation
+    switch ($token_definition['op']) {
+      case self::OPERATOR_API3:
+        if (preg_match(self::VALUE_API_CALL, $token_definition['val'], $match)) {
+          // verify api entity.action
+          try {
+            $actions = civicrm_api3($match['entity'], 'getactions');
+            $action_found = FALSE;
+            $our_action = strtolower($match['action']);
+            foreach ($actions['values'] as $known_action) {
+              if (strtolower($known_action) == $our_action) {
+                $action_found = TRUE;
+                break;
+              }
+            }
+            if (!$action_found) {
+              return E::ts("API3 action '%1' not found in entity '%2'", [1 => $match['entity'], 2 => $match['action']]);
+            }
+          } catch (Exception $ex) {
+            return E::ts("API3 entity '%1' not found", [1 => $match['entity']]);
+          }
+        } else {
+          return E::ts("API3 action should be defined as 'entity.action'");
+        }
+        break;
+
+
+      case self::OPERATOR_STATIC:
+        if (preg_match(self::VALUE_STATIC_FUNCTION, $token_definition['val'], $match)) {
+          if (!class_exists($match['class'])) {
+            return E::ts("Class '%1' not found", [1 => $match['class']]);
+          }
+          if (!function_exists($match['class'])) {
+            return E::ts("Function '%1' not found", [1 => $token_definition['val']]);
+          }
+        } else {
+          return E::ts("Function definition should be 'SomeClass::someFunction'");
+        }
+        break;
+
+
+      case self::OPERATOR_REPLACE:
+        try {
+          preg_replace(self::REGEX_DELIMITER . $token_definition['def'] . self::REGEX_DELIMITER, $token_definition['val'], 'doesntmatter');
+        } catch (Exception $ex) {
+          return E::ts("Ill-defined replace expression");
+        }
+        break;
+
+      default:
+        return E::ts("Unknown value type/operator '%1'", [1 => $token_definition['op']]);
+    }
+  }
+}
\ No newline at end of file