diff --git a/admin/settings/subsystems.php b/admin/settings/subsystems.php
index 81408bf3acc..10d1ea719a2 100644
--- a/admin/settings/subsystems.php
+++ b/admin/settings/subsystems.php
@@ -15,8 +15,28 @@ if ($hassiteconfig) { // speedup for non-admins, add all caps used on this page
 
     $optionalsubsystems->add(new admin_setting_configcheckbox('messaging', new lang_string('messaging', 'admin'), new lang_string('configmessaging','admin'), 1));
 
-    $options = array(DAYSECS=>new lang_string('secondstotime86400'), WEEKSECS=>new lang_string('secondstotime604800'), 2620800=>new lang_string('nummonths', 'moodle', 1), 15724800=>new lang_string('nummonths', 'moodle', 6),0=>new lang_string('never'));
-    $optionalsubsystems->add(new admin_setting_configselect('messagingdeletereadnotificationsdelay', new lang_string('messagingdeletereadnotificationsdelay', 'admin'), new lang_string('configmessagingdeletereadnotificationsdelay', 'admin'), 604800, $options));
+    $options = array(
+        DAYSECS => new lang_string('secondstotime86400'),
+        WEEKSECS => new lang_string('secondstotime604800'),
+        2620800 => new lang_string('nummonths', 'moodle', 1),
+        7862400 => new lang_string('nummonths', 'moodle', 3),
+        15724800 => new lang_string('nummonths', 'moodle', 6),
+        0 => new lang_string('never')
+    );
+    $optionalsubsystems->add(new admin_setting_configselect(
+        'messagingdeletereadnotificationsdelay',
+        new lang_string('messagingdeletereadnotificationsdelay', 'admin'),
+        new lang_string('configmessagingdeletereadnotificationsdelay', 'admin'),
+        604800,
+        $options)
+    );
+    $optionalsubsystems->add(new admin_setting_configselect(
+        'messagingdeleteallnotificationsdelay',
+        new lang_string('messagingdeleteallnotificationsdelay', 'admin'),
+        new lang_string('configmessagingdeleteallnotificationsdelay', 'admin'),
+        2620800,
+        $options)
+    );
 
     $optionalsubsystems->add(new admin_setting_configcheckbox('messagingallowemailoverride', new lang_string('messagingallowemailoverride', 'admin'), new lang_string('configmessagingallowemailoverride','admin'), 0));
 
diff --git a/lang/en/admin.php b/lang/en/admin.php
index 280c237552d..dd23cb0dcc5 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -275,6 +275,7 @@ $string['configmaxevents'] = 'Events to Lookahead';
 $string['configmessaging'] = 'Should the messaging system between site users be enabled?';
 $string['configmessagingallowemailoverride'] = 'Allow users to have email message notifications sent to an email address other than the email address in their profile';
 $string['configmessagingdeletereadnotificationsdelay'] = 'Read notifications can be deleted to save space. How long after a notification is read can it be deleted?';
+$string['configmessagingdeleteallnotificationsdelay'] = 'Read and unread notifications can be deleted to save space. How long after a notification is created can it be deleted?';
 $string['configminpassworddigits'] = 'Passwords must have at least these many digits.';
 $string['configminpasswordlength'] = 'Passwords must be at least these many characters long.';
 $string['configminpasswordlower'] = 'Passwords must have at least these many lower case letters.';
@@ -747,6 +748,7 @@ $string['mediapluginyoutube'] = 'Enable YouTube links filter';
 $string['messaging'] = 'Enable messaging system';
 $string['messagingallowemailoverride'] = 'Notification email override';
 $string['messagingdeletereadnotificationsdelay'] = 'Delete read notifications';
+$string['messagingdeleteallnotificationsdelay'] = 'Delete all notifications';
 $string['minpassworddigits'] = 'Digits';
 $string['minpasswordlength'] = 'Password length';
 $string['minpasswordlower'] = 'Lowercase letters';
diff --git a/lib/classes/task/messaging_cleanup_task.php b/lib/classes/task/messaging_cleanup_task.php
index 6d1a2c4d69f..15b781f9290 100644
--- a/lib/classes/task/messaging_cleanup_task.php
+++ b/lib/classes/task/messaging_cleanup_task.php
@@ -46,13 +46,18 @@ class messaging_cleanup_task extends scheduled_task {
 
         $timenow = time();
 
-        // Cleanup messaging.
+        // Cleanup read and unread notifications.
+        if (!empty($CFG->messagingdeleteallnotificationsdelay)) {
+            $notificationdeletetime = $timenow - $CFG->messagingdeleteallnotificationsdelay;
+            $params = array('notificationdeletetime' => $notificationdeletetime);
+            $DB->delete_records_select('notifications', 'timecreated < :notificationdeletetime', $params);
+        }
+
+        // Cleanup read notifications.
         if (!empty($CFG->messagingdeletereadnotificationsdelay)) {
             $notificationdeletetime = $timenow - $CFG->messagingdeletereadnotificationsdelay;
             $params = array('notificationdeletetime' => $notificationdeletetime);
             $DB->delete_records_select('notifications', 'timeread < :notificationdeletetime', $params);
         }
-
     }
-
 }