I have a similar problem. I get encrypted_only mails from my bank and I'm able to decrypt them via selecting and then context-menu-decrypt, but the button at the bottom of the page (gmail) says that FireGPG could not detect any signed or encrypted text. I haven't tried it with other mail (signed only, signed+encrypted) from other people, because nobody sends me encrypted mail :-(
- Mac OS X 10.6.1
- Firefox 3.5.3
- FireGPG 0.7.9
Edit: I just asked a friend to send me some encrypted mail. Well, FireGPG automatically detected it and asked me about my passphrase, decryption worked well, although the formating of the decrypted mail looks a little strange with lots of ">" and "/" at the wrong place. So it seems to be a problem with those particular encrypted mail from my bank. I could forward an example to a developer if neccessary.