you dont edit the universal email server behavior.
you need to edit the email templates where the verification links are generated.
the verification link in the email body will use the SecurityAssist_UserID session variable for the id in the URL
you need to change the value of the id url variable:
.....?id=<?php echo $_SESSION['SecurityAssist_UserID']; ?>&...
to use the UserID session instead of the SecurityAssist_UserID session:
.....?id=<?php echo $_SESSION['UserID']; ?>&...