diff --git a/Modules/Course/classes/class.ilObjCourseGUI.php b/Modules/Course/classes/class.ilObjCourseGUI.php
index 036ee0713845..857d9c7d5064 100755
--- a/Modules/Course/classes/class.ilObjCourseGUI.php
+++ b/Modules/Course/classes/class.ilObjCourseGUI.php
@@ -1010,7 +1010,8 @@ public function updateObject()
                 ilObjectServiceSettingsGUI::BADGES,
                 ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS,
                 ilObjectServiceSettingsGUI::SKILLS,
-                ilObjectServiceSettingsGUI::BOOKING
+                ilObjectServiceSettingsGUI::BOOKING,
+                ilObjectServiceSettingsGUI::EXTERNAL_MAIL_PREFIX
             )
         );
         
@@ -1483,7 +1484,8 @@ protected function initEditForm()
                     ilObjectServiceSettingsGUI::BADGES,
                     ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS,
                     ilObjectServiceSettingsGUI::SKILLS,
-                    ilObjectServiceSettingsGUI::BOOKING
+                    ilObjectServiceSettingsGUI::BOOKING,
+                    ilObjectServiceSettingsGUI::EXTERNAL_MAIL_PREFIX
                 )
             );
 
diff --git a/Modules/Group/classes/class.ilObjGroupGUI.php b/Modules/Group/classes/class.ilObjGroupGUI.php
index b41a9d5a824d..2728d19b679c 100755
--- a/Modules/Group/classes/class.ilObjGroupGUI.php
+++ b/Modules/Group/classes/class.ilObjGroupGUI.php
@@ -663,7 +663,8 @@ public function updateObject()
                     ilObjectServiceSettingsGUI::TAG_CLOUD,
                     ilObjectServiceSettingsGUI::BADGES,
                     ilObjectServiceSettingsGUI::SKILLS,
-                    ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS
+                    ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS,
+                    ilObjectServiceSettingsGUI::EXTERNAL_MAIL_PREFIX
                 )
             );
 
@@ -1759,7 +1760,8 @@ public function initForm($a_mode = 'edit', $a_omit_form_action = false)
                         ilObjectServiceSettingsGUI::TAG_CLOUD,
                         ilObjectServiceSettingsGUI::BADGES,
                         ilObjectServiceSettingsGUI::SKILLS,
-                        ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS
+                        ilObjectServiceSettingsGUI::ORGU_POSITION_ACCESS,
+                        ilObjectServiceSettingsGUI::EXTERNAL_MAIL_PREFIX
                     )
                 );
 
diff --git a/Services/Object/classes/class.ilObjectServiceSettingsGUI.php b/Services/Object/classes/class.ilObjectServiceSettingsGUI.php
index a5d9798ce49c..d07f5eb1ee10 100644
--- a/Services/Object/classes/class.ilObjectServiceSettingsGUI.php
+++ b/Services/Object/classes/class.ilObjectServiceSettingsGUI.php
@@ -36,6 +36,7 @@ class ilObjectServiceSettingsGUI
     const SKILLS = 'cont_skills';
     const FILTER = 'filter';
     const BOOKING = 'cont_bookings';
+    public const EXTERNAL_MAIL_PREFIX = 'mail_external_prefix';
 
     private $gui = null;
     private $modes = array();
@@ -307,6 +308,14 @@ public static function initServiceSettingsForm($a_obj_id, ilPropertyFormGUI $for
             $form->addItem($book);
         }
 
+        if (in_array(self::EXTERNAL_MAIL_PREFIX, $services)) {
+            $externalMailPrefix = new ilTextInputGUI($lng->txt('obj_tool_ext_mail_subject_prefix'), self::EXTERNAL_MAIL_PREFIX);
+            $externalMailPrefix->setMaxLength(255);
+            $externalMailPrefix->setInfo($lng->txt('obj_tool_ext_mail_subject_prefix_info'));
+            $externalMailPrefix->setValue(ilContainer::_lookupContainerSetting($a_obj_id, self::EXTERNAL_MAIL_PREFIX, ''));
+            $form->addItem($externalMailPrefix);
+        }
+
         return $form;
     }
 
@@ -424,6 +433,10 @@ public static function updateServiceSettingsForm($a_obj_id, ilPropertyFormGUI $f
             ilContainer::_writeContainerSetting($a_obj_id, "filter_show_empty", (int) $form->getInput("filter_show_empty"));
         }
 
+        if (in_array(self::EXTERNAL_MAIL_PREFIX, $services)) {
+            ilContainer::_writeContainerSetting($a_obj_id, self::EXTERNAL_MAIL_PREFIX, $form->getInput(self::EXTERNAL_MAIL_PREFIX));
+        }
+
         return true;
     }
 
diff --git a/lang/ilias_de.lang b/lang/ilias_de.lang
index 21307bd3d313..cad1937ce16d 100755
--- a/lang/ilias_de.lang
+++ b/lang/ilias_de.lang
@@ -13845,6 +13845,8 @@ badge#:#badge_user_profile#:#Benutzerprofil
 badge#:#badge_badge#:#Badge
 obj#:#obj_tool_setting_badges#:#Badges
 obj#:#obj_tool_setting_badges_info#:#Wenn aktiviert können Badges konfiguriert werden.
+obj#:#obj_tool_ext_mail_subject_prefix#:#E-Mail-Betreff Prefix
+obj#:#obj_tool_ext_mail_subject_prefix_info#:#Tragen Sie hier einen kurzen Text ein, der in die Betreffzeile von externen E-Mails in den Betreff aufgenommen wird. Dies erleichtert das Identifizieren von E-Mails aus unterschiedlichen Bereichen.
 badge#:#badge_add_template#:#Template hinzufügen
 badge#:#badge_image_template_form#:#Bildvorlage
 badge#:#badge_image_from_upload#:#Bild hochlanden
diff --git a/lang/ilias_en.lang b/lang/ilias_en.lang
index b22b5ceaa5a4..365fac171c34 100755
--- a/lang/ilias_en.lang
+++ b/lang/ilias_en.lang
@@ -13829,6 +13829,8 @@ badge#:#badge_user_profile#:#User Profil
 badge#:#badge_badge#:#Badge
 obj#:#obj_tool_setting_badges#:#Badges
 obj#:#obj_tool_setting_badges_info#:#Activates badge management and badge assignments to members.
+obj#:#obj_tool_ext_mail_subject_prefix#:#Mail Subject Prefix
+obj#:#obj_tool_ext_mail_subject_prefix_info#:#Enter a short text that is added to the subject line of external mails send to members to make identifying these mails easier.
 badge#:#badge_add_template#:#Add Template
 badge#:#badge_image_template_form#:#Image Template
 badge#:#badge_image_from_upload#:#Upload Image