Auto-mail filters and penet-remiler loophole?

Hm. Seems someone sent a message to my frienly-mailer filter using penet remailer. So of course that person will get an anonymized reply, thus being able to know what my anon-id there is. Fortunetly I don't use penet or rely on it for any form of security. That's one situation where it would be nice to specify in a line somewhere *not* to anonymize mail sent through there (a command in header saying X-Do-Not-Anonymize maybe?) Rob.