diff --git a/rule/eventnotification/lang/de/datalynxrule_eventnotification.php b/rule/eventnotification/lang/de/datalynxrule_eventnotification.php
index 9116ad36..7a0fc6b8 100644
--- a/rule/eventnotification/lang/de/datalynxrule_eventnotification.php
+++ b/rule/eventnotification/lang/de/datalynxrule_eventnotification.php
@@ -24,3 +24,5 @@
 $string['event'] = 'Datalynx Ereignis';
 $string['pluginname'] = 'Ereignisbenachrichtigung';
 $string['triggerspecificevent'] = 'Nur bei markierter Checkbox senden';
+$string['regex'] = 'Regulärer Ausdruck, der verwendet wird, um die Kennung aus dem Dateinamen zu extrahieren';
+$string['regex_desc'] = 'Wenn leer gelassen, wird es standardmäßig auf /^(\d+)_/ gesetzt.';
\ No newline at end of file
diff --git a/rule/ftpsyncfiles/lang/de/datalynxrule_ftpsyncfiles.php b/rule/ftpsyncfiles/lang/de/datalynxrule_ftpsyncfiles.php
index 0adb06d1..c69e39a7 100644
--- a/rule/ftpsyncfiles/lang/de/datalynxrule_ftpsyncfiles.php
+++ b/rule/ftpsyncfiles/lang/de/datalynxrule_ftpsyncfiles.php
@@ -37,3 +37,5 @@
 $string['teammemberfield'] = 'Formularfeld, das verwendet wird um den User zu bestimmen, dem die Datei zugeordnet werden soll';
 $string['manager'] = 'Der User, der die Einträge verwaltet';
 $string['filefield'] = 'Feld in dem die Datei gespeichert werden soll';
+$string['regex'] = 'Regulärer Ausdruck, der verwendet wird, um die Kennung aus dem Dateinamen zu extrahieren.
+Wenn leer gelassen, wird standardmäßig /^(\d+)_/ verwendet.';
\ No newline at end of file
diff --git a/rule/ftpsyncfiles/lang/en/datalynxrule_ftpsyncfiles.php b/rule/ftpsyncfiles/lang/en/datalynxrule_ftpsyncfiles.php
index 71ec1165..1bdd0cc7 100644
--- a/rule/ftpsyncfiles/lang/en/datalynxrule_ftpsyncfiles.php
+++ b/rule/ftpsyncfiles/lang/en/datalynxrule_ftpsyncfiles.php
@@ -37,3 +37,5 @@
 $string['teammemberfield'] = 'Form field to use for selecting the user the file is assigned to';
 $string['manager'] = 'User who manages all entries';
 $string['filefield'] = 'Field where the file should be saved';
+$string['regex'] = 'Regular expression used to extract the identifier from the filename.
+If left empty it defaults to /^(\d+)_/.';
diff --git a/rule/ftpsyncfiles/rule_class.php b/rule/ftpsyncfiles/rule_class.php
index 9b9d0abb..35f6ec5d 100644
--- a/rule/ftpsyncfiles/rule_class.php
+++ b/rule/ftpsyncfiles/rule_class.php
@@ -67,16 +67,10 @@ class datalynx_rule_ftpsyncfiles extends datalynx_rule_base {
      */
     private \mod_datalynx\datalynx $dl;
     private ?file_storage $fs;
-    /**
-     * @var false|int
-     */
-    private $draftitemid;
-    /**
-     * @var mixed
-     */
     private array $sftpsetting;
     private ?int $filefieldid;
     private array $files;
+    private $regex;
 
     /**
      * Class constructor
@@ -98,6 +92,7 @@ public function __construct($df = 0, $rule = 0) {
         $this->teammemberfieldid = $this->rule->param8;
         $this->authorid = $this->rule->param9;
         $this->filefieldid = $this->rule->param3;
+        $this->regex = $this->rule->param6;
     }
 
     /**
@@ -118,11 +113,10 @@ public function trigger(\core\event\base $event) {
         $this->dl = new mod_datalynx\datalynx($did);
 
         $this->fs = get_file_storage();
+        // Download files to $this->files array indexed by draftitemid.
         $this->download_files((int)$did);
         $context = context_user::instance($USER->id);
 
-        // $files = $this->fs->get_area_files($context->id, 'mod_datalynx', 'draft', $this->draftitemid);
-
         if (!empty($this->files)) {
             foreach ($this->files as $draftitemid => $file) {
                 $data = new stdClass();
@@ -222,24 +216,35 @@ private function download_files(int $did): void {
     }
 
     /**
-     * Find out the user the uploaded file belongs to based on the filename
+     * Find out the user the uploaded file belongs to based on the filename.
+     * Regex defaults to ^idnumber_
+     *
      * @param string $filename
      * @return int
      */
     protected function get_userid_from_filename(string $filename): int {
         global $DB;
+        // Extract user identifier from filename using a pattern.
+        if (empty($this->regex)) {
+            $this->regex = "/^(\d+)_/";
+        }
+        if (preg_match($this->regex, $filename, $matches)) {
+            $identifier = $matches[1];
+        } else {
+            return 0;
+        }
         switch ($this->matchingfield) {
             case 'idnumber':
-                $userid = $DB->get_field('user', 'id', array('idnumber' => $filename));
+                $userid = $DB->get_field('user', 'id', array('idnumber' => $identifier));
                 break;
             case 'email':
-                $userid = $DB->get_field('user', 'id', array('email' => $filename));
+                $userid = $DB->get_field('user', 'id', array('email' => $identifier));
                 break;
             case 'id':
-                $userid = $filename;
+                $userid = $identifier;
                 break;
             case 'username':
-                $userid = $DB->get_field('user', 'id', array('username' => $filename));
+                $userid = $DB->get_field('user', 'id', array('username' => $identifier));
                 break;
             default:
                 $userid = 0;
diff --git a/rule/ftpsyncfiles/rule_form.php b/rule/ftpsyncfiles/rule_form.php
index 76ded2e4..be456cc5 100644
--- a/rule/ftpsyncfiles/rule_form.php
+++ b/rule/ftpsyncfiles/rule_form.php
@@ -104,6 +104,11 @@ public function rule_definition() {
         $fields = $this->_df->get_fields_by_type('file', true);
         $mform->addElement('autocomplete', 'param3',
                 get_string('filefield', 'datalynxrule_ftpsyncfiles'), $fields, $options);
+
+        // Regular expression for extracting the user identifier from the filename.
+        $mform->addElement('text', 'param6', get_string('regex', 'datalynxrule_ftpsyncfiles'));
+        $mform->setType('param6', PARAM_TEXT);
+
     }
 
     /**
diff --git a/rule/ftpsyncfiles/version.php b/rule/ftpsyncfiles/version.php
index 5939f754..bed977e0 100644
--- a/rule/ftpsyncfiles/version.php
+++ b/rule/ftpsyncfiles/version.php
@@ -17,11 +17,11 @@
  *
  * @package datalynxrule
  * @subpackage ftpsyncfiles
- * @copyright 2023 Thomas Winkler
+ * @copyright 2023 Thomas Winkler, David Bogner
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 defined('MOODLE_INTERNAL') or die();
 
 $plugin->component = 'datalynxrule_ftpsyncfiles';
-$plugin->version = 2023101001;
+$plugin->version = 2023102300;
 $plugin->requires = 2014051200;
\ No newline at end of file