[Mailman-Users] MTAs

[Brad Knowles]

At 11:55 AM -0800 2005-03-25, Heather Madrone wrote:

>  The OSX setup, however, is only a stopgap while I get my permanent
>  server set up.  I've been looking for an open source operating system
>  that will run well on our Ultra 5 (sparc).  We were going with Debian,
>  which then announced that it's dropping sparc support, so we've switched
>  to OpenBSD.

	In terms of providing good support for UltraSPARC, Solaris is 
going to be best, and I believe that Solaris 10 is freely available 
from Sun.  But that's not what I would consider an "open source" 
operating system.

	In terms of Open Source operating systems for UltraSPARC, NetBSD 
is probably going to be the best, with OpenBSD close behind (they 
split off from NetBSD not too long ago), and FreeBSD catching up very 
quickly.  There may be some Linux distributions which also support 
UltraSPARC, and they might have been decent in the past, but I think 
they're tending to drop it in the same way that Debian has done.

>  The time has come to start seriously thinking about the MTA.  OpenBSD
>  comes with sendmail, but I'm not going down that road again.  I've heard
>  good things about postfix, but I've never used it.  It seems somewhat more
>  complex to set up than exim, and its integration with Mailman does not
>  seem to be as seamless.

	Postfix is a good MTA for use with mailing lists.  It does a lot 
of things out-of-the-box that you want in this kind of environment, 
and which take more work to do if you want to use sendmail instead. 
I have run large sites with both sendmail and postfix, and depending 
on what you're trying to do and how much care & feeding you're 
willing/able to give it, either sendmail or postfix should be 
perfectly suitable.

	I know a lot less about Exim, but it does seem to be reasonably 
capable, and I have spoken to the author of Exim a fair amount.  Phil 
Hazel is a good guy.  Based more on that than anything else, I 
consider Exim to be the only other MTA that I can recommend that 
people use.


	In terms of integration with Mailman, I think postfix is about as 
good as anything else I've seen, and the hacks to improve the 
integration with sendmail basically amount to lying to Mailman and 
instead telling it that it's using postfix.

>  My previous service provider used postfix, and we had recurrent problems
>  with Mailman's queues getting silently hung up.  A friend of mine who
>  runs a Mailman/postfix site also has the same problem.

	Hung up?  In what way?

>                                                          I wrote a perl
>  script to check for this problem and restart Mailman's qrunner if necessary,
>  and my Mailman/exim installation hasn't had this problem once.  Is this
>  problem related to postfix or have I just been lucky?

	I've never heard of a problem like this being able to be 
attributed to postfix and not be generally applicable to other MTAs 
as well.

>  	* Exim's ability to directly poke the Mailman installation and
>  	determine legitimate delivery addresses.

	If you use the postfix integration scripts, then the aliases are 
automatically generated when you create and delete mailing lists, and 
this shouldn't be a problem.

>  	* Exim's ability to handle VERP processing through the MTA
>  	rather than having Mailman have to do it.

	Postfix has support for XVERP, and there have been patches posted 
which allow Mailman to take advantage of that.  I don't personally 
like that option, as I don't think it really saves you anything, and 
it certainly takes a lot of the control away from Mailman that I 
would normally want to maintain.  But if you want this, you can do it 
with postfix.

>  	* Exim's fine degree of control of transient and permanent
>  	delivery errors (by host, by address, by error type).

	I'm not sure I understand what you're talking about.  Can you be 
more specific?  I know that postfix gives you a lot of control in 
these areas, but without knowing more about how Exim does them, it's 
hard to compare.

>  	* Exim's informative logs.

	I've seen Exim's logs.  I was never able to make much of any 
sense out of them.  I've also seen postfix's logs, and they seem to 
me to be the model of readability and understandability.

	Is there something in specific you don't like?

>  	* Ease of configuration and administration.

	Postfix is the only MTA on the planet that can have a truly 
useful two-line configuration file.  Moreover, it has the most 
intelligible configuration file that I have ever seen.  Better still, 
it comes up "default secure", unlike every other MTA I've ever seen.

	I've seen Exim configuration files, and it's hard to tell what 
goes where, what is a router versus all the other ways that certain 
things could be handled, etc....


	When looking at Exim and Mailman, there is a distinct issue that 
has to be kept in mind.  The instructions for integrating Mailman 
2.0.x are oriented exclusively towards Exim 3.x, and the instructions 
for integrating Mailman 2.1.x are oriented exclusively towards Exim 
4.x.  If you've got Exim 3.x and you want to use Mailman 2.1.x, 
you're screwed.

	Been there, done that.  Not knowing Exim very well, I had to be 
the one to try to patch together something that would 
kinda-semi-sorta work with Mailman 2.1.x and Exim 3.x.  Not fun.  I 
might wish this kind of experience on my worst enemies, but not 
anyone else.


	This is at least one area where postfix does not share the same 
kind of problem -- the instructions and scripts provided with Mailman 
2.0.x and 2.1.x work with pretty much any version of postfix that has 
shipped within the last few years.

>  	* Reliability.

	All I can say is that the largest Mailman installations in the 
world (that I know of) exclusively use postfix.  You'd have to ask 
them why they went this route, but my personal belief is that postfix 
is more powerful, flexible, and scalable than Exim, or most anything 
else available.

>  What are some reasons that I would consider postfix instead of exim?

	Well, for a small site, it mostly comes down to personal 
preference.  Regardless of whether I think that postfix is 
head-and-shoulders above Exim or not, if you're familiar with Exim 
and you feel comfortable administering it, then you should seriously 
consider continuing to go that route.  Of course, your hosting 
provider might also fit into this picture -- if they're not familiar 
with Exim, then if you have any problems you may not be able to rely 
on their help.

	We use postfix on python.org for mailman-users and the other 
mailing lists we host, the freebsd.org folks use it for their mail 
servers, and lists.apple.com use it for theirs.  However, just 
because we use postfix does not necessarily mean that you have to.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.