diff --git a/phpBB/phpbb/notification/method/email.php b/phpBB/phpbb/notification/method/email.php
index 10318ea215..26855603cb 100644
--- a/phpBB/phpbb/notification/method/email.php
+++ b/phpBB/phpbb/notification/method/email.php
@@ -126,7 +126,7 @@ class email extends \phpbb\notification\method\messenger_base
 	public function mark_notifications($notification_type_id, $item_id, $user_id, $time = false, $mark_read = true)
 	{
 		$sql = 'DELETE FROM ' . $this->email_notifications_table . '
-			WHERE ' . (($notification_type_id !== false) ? (is_array($notification_type_id) ? $this->db->sql_in_set('notification_type_id', $notification_type_id) : 'notification_type_id = ' . $notification_type_id) : '') .
+			WHERE ' . (($notification_type_id !== false) ? (is_array($notification_type_id) ? $this->db->sql_in_set('notification_type_id', $notification_type_id) : 'notification_type_id = ' . $notification_type_id) : '1=1') .
 			(($user_id !== false) ? ' AND ' . (is_array($user_id) ? $this->db->sql_in_set('user_id', $user_id) : 'user_id = ' . (int) $user_id) : '') .
 			(($item_id !== false) ? ' AND ' . (is_array($item_id) ? $this->db->sql_in_set('item_id', $item_id) : 'item_id = ' . (int) $item_id) : '');
 		$this->db->sql_query($sql);
@@ -138,7 +138,7 @@ class email extends \phpbb\notification\method\messenger_base
 	public function mark_notifications_by_parent($notification_type_id, $item_parent_id, $user_id, $time = false, $mark_read = true)
 	{
 		$sql = 'DELETE FROM ' . $this->email_notifications_table . '
-			WHERE ' . (($notification_type_id !== false) ? (is_array($notification_type_id) ? $this->db->sql_in_set('notification_type_id', $notification_type_id) : 'notification_type_id = ' . $notification_type_id) : '') .
+			WHERE ' . (($notification_type_id !== false) ? (is_array($notification_type_id) ? $this->db->sql_in_set('notification_type_id', $notification_type_id) : 'notification_type_id = ' . $notification_type_id) : '1=1') .
 			(($user_id !== false) ? ' AND ' . (is_array($user_id) ? $this->db->sql_in_set('user_id', $user_id) : 'user_id = ' . (int) $user_id) : '') .
 			(($item_parent_id !== false) ? ' AND ' . (is_array($item_parent_id) ? $this->db->sql_in_set('item_parent_id', $item_parent_id, false, true) : 'item_parent_id = ' . (int) $item_parent_id) : '');
 		$this->db->sql_query($sql);