filtering signed email with thunderbird

[Sven Radde]

Hi!

Am Freitag, den 02.05.2008, 12:55 +0200 schrieb Ramon Loureiro:
> Is it possible to make a thunderbird filter that save my signed msgs
> in
> some folder?

I don't think it's trivially possible (i.e. without coding something
yourself), but I think it would be a great feature to add (to
Enigmail?).

> What in the email header must the filter check to see it has a (valid)
> signature?

The signature is not just some "valid" flag inserted into the email
headers. Your mail client will perform a calculation on the email's body
whenever you open it and then decide whether the mail was modified since
it was signed.

> Or must it look for "BEGIN PGP..." strings into the body of the msg?

You can do that, but that filter would apply to every
PGP-signed/-encrypted message, no matter whether the signature is valid
or not.
However, AFAIK you won't get anything that uses PGP/MIME with that
filter. You would have to check for the corresponding Content-Type
header for these messages.

cu, Sven