(this bug seems related to 2076)

claws-mail build against gpgme-1.2.0 does not correctly decrypt or encrypt mails using the s/mime-plugin.

What happens:

-Encrypting a mail using s/mime and sending it ends up with a double-base64ed smime.p7m.
-Decrypting a mail which is double-base64ed works fine (although maybe no other mail-client does that)
-Decrypting a mail sent by other mail clients (thunderbird, outlook) fails, since it isn't double-base64ed.

How to check if the message is double base64ed:

-Sign&Encrypt a mail using claws
-look into the message source
-if the attachement smime.p7m starts with "TUlBR0" it's double-encoded
-if it starts with "MIAGC" it is correct

How to check that this really is what eg. claws and thunderbird keeps from communicating with each other over s/mime:

-Send a mail in either direction
-edit it with your favourite text editor
 -either base64-decode or base64-encode the data of smime.p7m (encode it if was sent by thunderbird and you want it to decrypt with double-base64-claws, or other way round if sent by claws and you want to decrypt it in thunderbird)

Ps.: apart from this bug (show-stopper without a text-editor), s/mime now works way better between thunderbird(v3.0.3) and claws. Thunderbird does not seem to send RC2-40 Mails anymore.