Reference: http://www.howtoforge.com/forums/showthread.php?t=53938

nveid

2011-08-29 0ea2a52fe228fd482f4cb4ce9440c22b8c37d9da

 server/plugins-available/maildrop_plugin.inc.php

@@ -60,6 +60,7 @@
      Register for the events
      */
      
      $app->plugins->registerEvent('mail_user_insert','maildrop_plugin','update');
      $app->plugins->registerEvent('mail_user_update','maildrop_plugin','update');
      $app->plugins->registerEvent('mail_user_delete','maildrop_plugin','delete');