Excerpts from info-mime: 20-May-94 Re: application/postscript .. Bill
Actually, nearly all of the formatted mail I get from Andrew users
(mostly other Andrew users at PARC, and the Andrew Consortium's Andrew
mailing list) is in Andrew format (non-MIME, Content-Type: X-BE2; 12).
But maybe that's a local peculiarity.
Yes, the default setting depends on the local Andrew installation. I'm
not sure what the out-of-the-box default is nowadays, your experience
would suggest that it's X-BE2.....