[Mailman-Users] Suggestions for Queuing bulk mailings?

[J C Lawrence]

On Mon, 1 Oct 2001 15:22:40 -0400 
Jim Kutter <jim at ebizq.net> wrote:

> Also can anyone give me hard times for qmail+mailman with a very
> large list (> 30K members)? I've heard it's "really fast" but that
> doesn't help me make the sale for qmail...

Hard stats in the MTA field are difficult if not impossible to
achieve.  There are just too many external factors such as variant
RTT, percentage and distribution of slow MXes, distribution of
target MXes and their percentage distribution over the load, size of
RCPT TO bundling, etc etc etc.  Statistically, its a large and
thorny problem with any particular numbers derived in one instance
likely not applicable elsewhere except as a hint.

The most fundamental aspect of MTAs is that they are really not
limited by MTA software performance.  They are limited by disk IO.
While there are minor differences in the exact behaviour of the
different MTAs when they run up against the disk IO wall, the
numbers when they all do are remarkably similar.  This shouldn't be
surpising when you consider the requirements for commited writes via
open()/fsync()/close().

There are three performant MTAs currently on the Open Source market:
Exim, Postfix, and QMail.  

  Exim is a monolothic design much in the manner of SMail, from
  which it was derived.  The author, Philip Hazel, is responsive and
  helpful.  It has excellent documentation, an active support
  community and the most human readable and understandable config
  files of any MTA I've seen.  it also happens to come with an
  excellent Mailman HOWTO.  In tests here Exim's performance
  curves were similar to Postfix's, with a lower attack curve and
  similar delivery rates at the inflection points of constantly-busy
  and queue-saturated.  Exim is particularly good (and aggressive)
  about maintaining a persistent hints database for slow MXes.  If
  slow MX processing forms a significant percentage of your spool
  handling.  Exim also has extensive config options for
  minimising/controlling load distribution on the host system which
  can be useful for multi-purpose servers or timed load
  distribution.

  Postfix used a distributed minumum trust design that's somewhat
  similar to QMail's.  The main differences in its design as
  compared to QMail is that Postfix compromises less with standard
  interfaces and file system standards.  The author, Wietse Venema,
  is responsive and helpful, and has a long and largely illustrious
  history in the security community (author of TCP wrappers etc).
  The Postfix documentation is thorough but sparse.  The config
  files are easily read, but are not as clear as Exim's.  In tests
  here Postfix's delivery rates were similar to Exim's with a
  higher initial attack curve (and subsequent higher system
  loading) but similar values at the inflection points.  Postfix's
  queue handling si similarly intelligent to Exim's with the
  exception that Postfix does not maintain a slow MX hints DB.

  I didn't bother evaluating QMail.  I've little patience with DJB
  deliberate abrasiveness, less interest in the violence he delivers
  to the FHS, and just can't be bothered with his lack of licensing.
  Not worth the time or bother.  Cursory examination of other's
  stats (such as Amanda's) suggests that its performance and load
  curves are very similar to Postfix's.

-- 
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.