dhc(_at_)dcrocker(_dot_)net (Dave Crocker) wrote on 17.06.04 in
<218049616(_dot_)20040617034033(_at_)brandenburg(_dot_)com>:
Tony,
good comments. here are some good responses to them...
TF>> e2) transport layer i.e. SMTP.
TF>> Other implementations include LMTP, batch SMTP, UUCP, and way back in the
TF>> ARPANET days, FTP.
Rather than being a general discussion of global email, I decided to
limit references to current Internet specifications. Hence, the FTP
MAIL and MLFL commands have died away and UUCP was never part of the
set. That does not make them any the less important, merely not
within scope for a current description of the main stream of Internet
mail.
Actually, I'm pretty certain UUCP was part of it, and still continues in
some places on the edges. It wasn't ever specified by a RFC (but then,
interaction between UUCP and 822 addressing *was* specified - RFC 976).
My personal experience with this does not include UUCP routing - that was
pretty much gone before my time - but does include UUCP mail transport; in
fact, that is still what one of my current MXes uses to get mail to me,
with UUCP-over-ssh. (More popular is UUCP-over-TCP, port 540.)
There are two rather different ways (with a number of subobtions that are
irrelevant to the discussion) to handle this. One can either use rmail -
that is, convert the SMTP envelope into a UUCP envelope (presumably
reverting this on leaving UUCP) - or one can transport BSMTP via UUCP,
thus keeping as much inside SMTP as possible. (The suboptions consider
stuff like how or if to compress this.)
Obviously, the rmail variant is essentially a double gateway, not much
different from using the various LAN mail systems (Exchange, Groupwise,
Notes, whatever). The BSMTP variant, on the other hand, seems to be more
worth mentioning. (*Do* we have a RFC about BSMTP?)
MfG Kai