Rated 5 out of 5 stars

Great add-on! I am waiting for something like this for a long time. Don´t you think about na other add-on else? TB doesn´t know to associate a S/MIME certificate with a contact. Sometimes you get a digitally signed mail but you need to encrypt the reply with an other certificate. But TB automatically uses the signing certificate and you cannot simply choose the certificate you need... (http://forums.mozillazine.org/viewtopic.php?f=39&t=770435, http://forums.mozillazine.org/viewtopic.php?f=39&t=727475)