Can someone explain to me (and the list if appropriate) whether
there's any current or planned coordination between MIME type
registration and the activity in the Electronic Messaging
Asossication's Message Attachment Work Group?
Yes there is. Its happening in the MIXER working group of the IETF, which
is responsible for handling X.400 to RFC822/MIME mappings. FTBP is part
of this mess, and the group is now "discussing" the matter.
Most of the RFCs that deal with X.400 (or at least, those that have
X.400 in their title) seem to deal with addresses, not content-type.
Not really. See RFC1496 and its brethren.
Does anyone have a relatively complete set of references on mail
standards, e.g., in a web page?
Let me know if you find it!
Ned