The signature-changing functionality of the MailEnhander plugin for OS X Mail.app doesn’t work with Tiger (10.4.1). This is a major bummer. The sig-changing functionality was the only reason that I used MailEnhancer.
It looks like Mail.app changed its behavior to aggressively reset the signature (presumably after MailEnhancer changed it).
What’s worse is that the author has disappeared. His web page has gone 404, and no one seemed to know where he is. So no one has the source code to MailEnhancer, and there’s a lot of other bummed users out there.
Bonk.