The problem with your idea about tagging mail as clean is that "the bad side" will fake such signatures. So in general it is no good idea to trust mail header tags in general like mail body signature strings.
Alex,
Thanks for the reply. In your opinion, is it cryptologically feasable to generate a signature system that cannot be easily faked? It seems that if rpms can be verified against GPG keys, then the same could be applied to email. Would this be sufficient security? I do not know, but I believe it is worth discussion.
Thanks,
Dale
