I also see this bug, but I think enigmail is actually noticing the message is signed - if I disable automatic message verification/decryption, I get a message "Possibly PGP/MIME encrypted or signed message; click Decrypt button to verify". Of course, there is no "decrypt" button visible to click.
I also have display mail user agent installed, so I thought it might be an interaction with that; disabling that extension doesn't seem to affect that bug.
I also see this bug, but I think enigmail is actually noticing the message is signed - if I disable automatic message verification/ decryption, I get a message "Possibly PGP/MIME encrypted or signed message; click Decrypt button to verify". Of course, there is no "decrypt" button visible to click.
I also have display mail user agent installed, so I thought it might be an interaction with that; disabling that extension doesn't seem to affect that bug.
This is for Ubuntu 10.04 (Lucid) on amd64.
--Anil