CF_URLSafeEncryption will encrypt any string you send to it and return a value that's safe for URL use. I made it because I sometimes have mailing lists where I give the option to have the person remove themself from it. However, some of these sites do not offer login access due to time restrainsts to get the code done (and this is the only feature for general users). What I generally do is encrypt the record ID field and the email address.