On Tue, Aug 13, 2024 at 3:06 PM Clem Cole <clemc@ccc.com> wrote:
> On Tue, Aug 13, 2024 at 2:13 PM <arnold@skeeve.com> wrote:
>> ... CSNet didn't happen until the mid-80s, by which time
>> sendmail was firmly entrenched in the BSD world. ...
>
> Right -- my bad.  CSNET did not occur until a few years after I had finished my grad work and left.  ISTR CSNET used MMDF as the mail transport agent (not sendmail).  But my point was that there were numerous alternate mail systems, commercial and independent, that had "portals" into and out of the USENET and the ARPANET and later the Internet - so email headers were getting warped in strange ways and trying to be able to reliably reply was often difficult.

I tried to set up MMDF on an RT running AOS once; this was during the
era when Sendmail was getting hacked nearly continuously.  It was kind
of a nifty architecture; different formats used different "channels"
feeding into a common routing core.

It sort of broke down because the inter-message separately wasn't
compatible with any clients we were using; they didn't use the BSD
"mbox" format, but rather, used a set of (4?) `^A`'s as the message
separator.

I'm sure there was some way to change this, but I never investigated
sufficiently to figure out what it was.

> Eric was having to deal with some new hacks fairly regularly, and the idea of a production language to convert format A to B to C was a good one.  The only real mistake in my mind was that (unlike MMDF) he built the SMTP daemon in sendmail. MMDF and some of the other systems had programs that converted to/from a canonical form (usually RFC733/822 style) and then some sets of external utilities that talked to the "port" - be it UUCP, SMTP, "PhoneNet", or whatever.   But making it built into sendmail itself, in fact, was a violation of the UNIX "do one job well" idea and would, of course, be the attack vector.   The two sad parts of that IMO is that first most people did not need most of the features of sendmail -- they needed just SMTP and maybe UUCP, but send sendmail was the SMTPD for BSD, that is what they had.  But the BBN TCP/IP package that UCB started with had a separate SMTPD and Eric could have just called it like he did the UUCP subsystem.
> ᐧ

Zmailer had an architecture kind of like that; at least some folks
were running it locally. But it never really caught on, as far as I
could tell, and eventually qmail and postfix (nee vmailer) provided a
better alternative. I guess some folks still swear by Exim.

I kind of wonder if the days of Unix MTAs as anything other than a
detail are mostly over.

        - Dan C.