Why would you want a MIME encoding solution in the default installation? I mean, really, what do a large majority of systems need MIME for?
1) Character set support. These days I suspect the number of Unix users who can live completely within the US-ASCII glyph set are in the minority.
2) PGP/MIME and S/MIME. Even without doing crypto processing, MIME lets the MUA display only the human readable parts without contortions.
MIME has been around for 14 years. There's no excuse for any MUA not to be able to deal with it at least minimally. In the case of /usr/bin/Mail that means recognizing content types and only displaying text/* sections when printing to the screen. It doesn't *have* to be complicated.
--lyndon
