Should fix bug when sending announcements see #5394

main/announcements/announcement_email.class.php

@@ -148,15 +148,20 @@ class AnnouncementEmail
         
         if ($users) {
             $users = UserManager::get_user_list_by_ids($users, true);
-        } else {
-            $users = self::all_users();
         }       
 
         if (!empty($groups)) {
             $group_users = GroupManager::get_groups_users($groups);
             $group_users = UserManager::get_user_list_by_ids($group_users, true);
+            
+            if (!empty($group_users)) {
                 $users = array_merge($users, $group_users);            
             }
+        }        
+              
+        if (empty($users)) {
+            $users = self::all_users();
+        }
         
         //Clean users just in case
         $new_list_users = array();