[Angel-Wings]

Originally Posted by FF|Skyrider

Can you solve this issue if possible?

Problem is that the MySQL commands aren't parsed correct so ' that "signs" the end of a value let MySQL think the entire Query ends here. Everything behind will produce an error.
Maybe - with weird some Email- / Board- or Username some injection can be possible.

About the sent mails - maybe a good idea to add an X-Mailer value as well that Antispam systems won't "jump" on the mail with a false-positive.

In "remindermail.php" something like:

$headers .= "Return-Path: " . $vbulletin->options['reminder_fromemail'] . "\r\n";
$headers .= "X-Mailer: Vbulletin Mailer\r\n";
$headers .= "X-Remindermail-BounceId: $userid\r\n";
$headers .= "X-Remindermail-BounceSalt: $salt\r\n";

Should do it.