We are running a custom registration PHP script that emails us when a user registers a purchased/evaluation of our software. Since 6.x release, Drupal has worked flawlessly for this. Now, after upgrading to 6.19, we get some "%40" in place of the @ symbol in the emails we receive (e.g. david123%40hotmail.com).

This is really annoying, as our admin has to go in and manually change the %40 to an @ symbol in hundreds of emails a day that we record.

Unfortunately I can't post up our PHP script, but our lead developer has looked at it and has said that it has nothing to do with the script.

Any advice on where in Drupal this may be causing the error?