OK. GNUMail.app just went into Sarge today. It is supposed to be like the NeXT/Apple Mail.app (neither of which I have used). I must say that it is really nice. I am seriously considering switching from Thunderbird. It has very nice and intuitive interfaces, native gpg integration (no plugin necessary), and a bunch of really nice features. My only beef is that there was no way to configure it for SMTP/TLS over port 25 (which is what my mailserver is set for), so I had to enable sslwrap on port 465. But that was only a minor annoyance. I heartily recommend anyone who uses a GUI MUA and is one of the *Step environments most of the time. -Roberto Sanchez
RFC3156 defines security multipart formats for MIME with OpenPGP.
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