[tekguru]

Just looked at the plugins, the only ones are:

Current User Update
Global Bounce Headers
Main
Options Processing
Required
Update Valid Email

and the nearest I can fine is:

if($vbulletin->GPC['email'] != $vbulletin->userinfo['email']){
  $vbulletin->db->query_write("UPDATE " . TABLE_PREFIX . "user SET bounced = '0', usergroup = reminder_oldgroup WHERE userid = '" . $vbulletin->userinfo['userid'] . "'");
}

in 'Update Valid Email'...

Confused?