[Mailman-Users] Re: MTAs

[Heather Madrone]

Thank you so much, Derrick.  This is exactly the sort of information
I was looking for.  Of particular interest was the discussion of exim's
and postfix's configuration, the performance benchmarks, and your
story of running the two MTAs through an underpowered router.

At 8:53 AM -0500 3/26/05, Derrick Hudson wrote:
>On Fri, Mar 25, 2005 at 11:55:46AM -0800, Heather Madrone wrote:
>[...]
>
>| We were going with Debian,
>| which then announced that it's dropping sparc support,
>
>Hold up.  Debian hasn't announced any such thing.  Don't pay attention
>to the rumors.  Some of the project's leadership *proposed* (notice
>that it's just a proposal) and different way of supporting 11+
>architectures and making releases manageable.

You're right.  I was trying to gloss over the details of a long search for
an adequate OS.  Suffice to say that the linuces have been dropping sparc
support left and right, and it looked like Debian might follow suit. 

>exim is only semi-easy to configure and administer.  postfix is
>easier.  exim's model requires you, the administrator, to put together
>all the pieces needed for mail handling (access control, routing,
>transports) and then it requires you to put the logic in place so that
>the right components interact the way you want them to.  The biggest
>drawback is the verbosity in the configuration file.  The second
>biggest drawback is the trickiness in correctly setting all the
>conditions to handle very unusual and strange situations.

Yes, this is true.  It took me a few weeks to fine-tune exim so that it
correctly handled all the usual occurrences in my mail world.

It's pretty easy to configure if you can read and think, however, something
that has not always been true in the Unix world.  I had it up and running
and working with Mailman in a few hours, and was marveling at how
smoothly it all went.

>I would say that exim is actually more flexible than postfix, since
>the admin controls so much of the logic.  However, postfix is simpler
>because Wietse already put all the logic in the code and the only
>responsibility of the admin is to fill in the tables correctly.

Are there any configuration options in exim that you miss (or missed)
in Postfix?  I like the ability to control retries, because I don't want more
network traffic than I need to keep my lists running smoothly.  Have you
ever wished for more control in that area, or does Postfix handle it all
so intelligently that you're glad to have it use its brain instead of yours?

>I agree -- exim 3 is extremely old, no longer maintained, and exim 4
>greatly simplified the configuration.  I think it has been three or
>four years, now, since exim 3 passed the torch on to exim 4, and I
>can't think of any -good- reason to use it other than perhaps "if it
>ain't broke, don't fix it" (but that includes not upgrading or
>installing a new mailman on the exim3 server).

One of my concerns with Debian is that Python programs tend to be
closely coupled with Python versions.  I was concerned that I might
be in a position where I'd be stuck in a version of Debian that wouldn't
work with a new version of Python (and hence Mailman).

>Heather wrote:
>> With exim, trying to do VERP processing on the digest runs caused
>> Mailman to flood exim, even when I turned the number of sessions and
>> connections way down.  It also brought my poor Mac, which was not
>> meant to be a server, to its knees.  I'm hoping that the sparc will
>> be able to handle peak loads more gracefully than a Powerbook.

(To be fair to the Powerbook, I was also asking it to be a laptop at the
time.  It could not handle heavy-duty web browsing at the same time
it was handling peak Mailman loads.  Moving VERP from Mailman
to exim and setting up a caching name server solved the problem.)

-- 
Heather Madrone  (heather at madrone.com)  http://www.madrone.com

A rolling stone gathers no mass.