Sendmail replacements?

Thu Feb 13 12:14:00 PST 2003

On Thu, 13 Feb 2003 11:49:45 -0500 
Rich Holland <holland at guidancetech.com> wrote:

> It's been several years since I did any significant SMTP work, and now
> I find that I've got to configure a bunch of machines and a central
> hub to relay mail for the others.  

Aye, that's called a "smarthost".

> My first thought was rewriting headers by changing the sendmail.cf
> file, but now that I think about it, this may be the time to replace
> sendmail with something "easier" or "better" or "more secure" but I'm
> out of touch with the state of the art in SMTP mailers.

You're going to be told about Exim, Postfix, Qmail and Sendmail.  Start
out by realising that this is a field rife with subjective opinion and
preferences reported as fact.

Of the lot above I've used Exim and Postfix extensively.  I like 'em
both.  Shockingly I like 'em for different reasons and use them in
different cases.

Postfix screams (in a non ear wax drilling way).  With minor effort on a
$2,000 box I find I can sustain 2,400 outbound deliveries per minute (to
Internet sites across the cloud).  That runs up to a few million a day
without blinking.  The configuration is trivial, well documented,
consolidated into two files, and pleasant.

Exim is a delight.  Extremely well documented and configurable out the
wazoo.  On the same $2,000 box with similar levels of effort to Postfix
I've gotten 2,200 outbound deliveries per minute with similar effort
levels.  

I run and use both.  I like both.  

  - Exim is absurdly configurable and extensible.  It rivals Sendmail
  for the number of buttons that can be tweaked.  Happily the vast
  majority have intelligent defaults and can be left alone.  More
  happily it has excellent documentation on the buttons.  

  - Exim is amazingly easy to integrate with external systems, tools,
  mail processing systems etc.  Postfix isn't bad in that regard, but
  Exim is better.  As a quick example for my TMDA integrations I needed
  alias pipes to be run as a specific UID/GID.  That's trivial under
  Exim and not under Postfix.  

    -- The above point warrants more attention.  Exim is amazingly good
    at integration.  SpamAssassin, TMDA, virus scanners, outbound mail
    processors, per address filtering, system wide filters, you name it.
    Exim just smiles and asks for more -- and all with a config file you
    can come back to two years later and understand on the first
    reading.

  - Exim is very friendly to localhost by default.  It has a number of
  knobs for things like system load, number of messages received etc,
  that make it easy to keep Exim friendly to other services running on
  the same box.  Similarly its easy to configure Exim such that it
  essentially never impacts localhost operation, even under large
  spools).

  - Exim doesn't handle large spools well.  There are a number of things
  you can do to improve that condition (like split spools), but the
  baseline remains: If you're heading into the hundreds of thousands of
  spool entries Exim is going to start to suffer.  There are some ugly
  contention points on the core control files in Exim which don't
  improve matters there.  Postfix handles large spools with considerably
  more ease, and has a flatter smoother scaling curve in that regard.

  - Philip Hazel (Exim author) and Wietse Venema (Postfix author) are
  pleasant, responsive, friendly, and generally good sorts that are
  about as much of a joy to work with as you could ever hope for.  Both
  have large active support communities for their MTAs.  

I see that Rick Moen (:waves) later quotes a quote of my comments on
them, so I'll leave that there.  I (and others) have made various
comments in the Mailman FAQ that you might find useful:

  http://www.python.org/cgi-bin/faqw-mm.py?req=index

> Anyone have any suggestions?

Boy, most people don't invite nuclear strikes.

-- 
J C Lawrence                
---------(*)                Satan, oscillate my metallic sonatas. 
claw at kanga.nu               He lived as a devil, eh?		  
http://www.kanga.nu/~claw/  Evil is a name of a foeman, as I live.