> From: scott @
COM (Scott Barman)
> To: firewalls @
> Subject: Is there another alternative to sendmail/smail? upas?
> In the past, unless age is eroding my memory :-), I recall some of the
> folks at AT&T mentioned the name of their mailer (upas). I also think
> it was mentioned in C&B (I think it's worthy of this moniker, like K&R!)--
> not having my copy in hand, I cannot verify this. Somewhere in my
> (deep-dark) past, I believe I read a paper about it by Dr. David Presotto
> (I think that's his name--I apologize if I am wrong). This triggers a
> few questions:
> 1) Where was that paper published and is it on line somewhere?
> 2) Is the source available to the general (non-AT&T) public?
> 3) As an alternative, did someone do their own port that might
> be available?
> 4) What would make it more secure than sendmail or smail?
WARNING: Since don't work at AT&T any more, don't take this as the final
answer, but as a somewhat fuzzy account of reality...
Upas is a mailer that was developed at AT&T Bell Labs.
I think it was done by Dave Prosotto and Bill Cheswick, though I could
easily be totally wrong on that account.
I don't think any papers were published outside of AT&T, though there
might be a USENIX paper on it, or at least mentions it in USENIX
papers (maybe ones on Plan 9).
Source probably isn't available to the public, though binaries for
Plan9 probably are ;-)
Upas is also the basis for the delivery agents in the original sVr4 mailer,
and some current sVr4-based systems, including UnixWare, use either
those mailers or successessors to them, including UnixWare.
(Note, the UnixWare mailer no longer closely resembles the original
upas, though many of the ideas of upas live on. Since I work here in
the center of the UnixWare universe, you'll have to consider my comments
on that product in that light. Also note that some sVr4-based systems,
such as Solaris 2.x, use Sendmail instead.)
The big advantage of upas and its commercial successors is that it's
split into lots of specialized little pieces instead of one big giant
Super Duper Do-Everything Mail Server. Also, it was originally
written by people who were thinking about security from the start,
instead of trying to fight fires later.
Christopher J. Calabrese
Network Security Architect
Novell Information Services & Technology, Florham Park, NJ