A comparison of Mail Transfer Agents - Part Two

exim = 15 points, postfix = 17 (from the chart)

If you're going to do a shameless plug for your favorite product. Either doctor your stats or come up with some real reasons to recommend one over the other.

OTOH postfix was a drop-in sendmail replacment, but with *much* higher performance than sendmail, and it turns out to be the default MTA in suse linux, while we were migrating all our infrastructure from redhat to suse. We've since discovered there are nice postfix packages for solaris and other unices as well.

We've found that doing spam/virus filtering and weird procmail tricks is really easy and convenient with postfix, so it has my vote.

As far as having a windoze version, that is of absolutely no importance to us, no idea why it was even mentioned. In fact, I think I'd give more points to a unix MTA that just strives to be the best, and doesn't waste cycles jumping through hoops, trying to produce a windoze version. We are a unix shop, you know. YMMV.

Sendmail: 1521746
Exim:     3640124
Postfix: 11521454

I don't think much weight should be given to either the 'run sendmail milters' or 'runs on Windows' rows. However, your table should probably include a row for 'overall capabilities', including such things as greylisting, integration with SpamAssassin/ClamAV/etc., mail filtering, ...

For what it is worth:

[I've used sendmail, postfix and qmail extensively. I no longer use sendmail, but still use postfix/qmail depending on the application.]

qmail - qmail isn't that hard to set up and manage. It is a bit different, but the are plenty of resources to help you get going, plus some simple installation scripts. I would give it a 2 or 3 on that score.

qmail's downfall is also its strength. It is very very simple, and almost simplistic. It can't do all the magic things you might need to do - but its simplicity makes it good from a security point of view - simple set of well defined functions, nicely broken down into separate processes. My "use case" for qmail is a front line email server, attached to the internet, doing simple relaying - into which I add AV and anti-spam. My qmail setups always relay on to another machine on the internal network.

For this mode of use the qmail install/config is completely trivial - the only changes to be made is a one line entry to the file which contains the list of "Known" domains, and the one which tells which internal server to route those domains to. In use qmail just gets on with it.

sendmail - sendmail is really hard to manage - unless you stick to cookbook examples - working with the m4 files is hard enough, but to directly manipulate the .cf file is something else.

postfix - postfix has a rich set up - and is very comprehensive, so you have to study the manual too. I think a 2 or 3 for postfix - certainly it is a bit more complex to maintain than qmail - which becomes trivial after it has been installed.

I use postfix were qmail doesn't have the necessary features - typically on an internal network, in conjunction with cyrus-imapd - at the point where the email system needs managing (defining aliases, routing rules etc, controlling the queue).

I've looked at exim, but never seen a compelling reason to switch from postfix.

Conclusion
----------
The tools are different, and apply themselves to different situations - it's great to have the choice and to use the best tool for the job.

Alright, this was years ago, when I was about to administer my first MTA server, it was setup to run sendmail. I spent a considerable amount of time to understand the elaborate configuration, but was unable to understand it fully. I decided to convert to qmail. It took some time to get used to all its principles, yet after the effort I felt that I understood the configuration completely.

This is a very good feeling I have not attained with any other MTA in a reasonable time frame. Since I was a complete newbie to MTA configuration, I would argue that qmail is considerably easier to setup.

That said the license restrictions of qmail make it an odd choice.

Sendmail clearly has the best Milter support and should get a 3. Postfix 2.3 has incomplete Milter support, so it should only get a 1 or 2, though I am keeping my eye on it for the day when Postfix completely supports Milter.

If Exim got a high score because it can do "equivalent" things to a Milter, then the author hasn't read the Milter API. It's far and away the best e-mail filtering API for any of the free MTAs, and possibly for any MTA.

You also score Postfix as essentially perfect for all situations except Windows and small systems, yet Exim, which doesn't score as well, is preferred. And the reason for that is *not specified*... you simply say that Exim does everything and Postfix doesn't. You spend all this time reviewing mailers, but when it actually comes down to why we should choose one over the other, the cited reason is nebulous and unspecified. Sheesh!

In my years with Postfix, I have found only one situation where it didn't cope well... at one time, it didn't speak Maildir, so I had to tie it into maildrop to support those. (I think that's been added since.) It's very fast, very configurable, and *incredibly* robust. NASA's rovers crash more often. And in all its history, I remember seeing only one security bug.

For my uses, I'd rather trade off a little bit of unspecified functionality to get better security. I'm not belittling Exim, as I don't know it well enough to judge it, but I can certainly say that Postfix is grade AAA, and one of the single best pieces of free software.

This is not a recommendation for running sendmail. While I like the software having written rules since 1991 or so.. I also realize that I know enough about it to make sendmail perform better than an out of the box postfix or exim.. which of course makes me a very biased opinion. But I do think that reports about how many vulnerable systems out there need to be looked at a bit more sceptically.

Giving sendmail a zero for "*sendmail* milter" support is assinine. Giving it a zero for "worried about security" is ludicrous in context of the last several years -- it only makes sense if you are comparing complete histories, and even that's not entirely fair given how much longer a history sendmail than all the others. They learnt all the hard lessons for everyone else.

You gave sendmail a zero on "wanting minimum hassle" even though your own text states that "sendmai works with little or no modification to the default settings"! For that matter, shouldn't that also affect the score for inexperience users?!

Size constraints? Have you looked at the compiled footprint of the other daemons?

Yes, I am a sendmail user. I know it has warts, but I also know I've evaluated several other alternatives and found none of them to have the flexibility and scalability for complex ISP & Enterprise environments.

Your scoring system is inconsistent with even the facts you presented and is utter rubbish.

At this time the first line should read 8 years rather than 6.

Posted May 27, 2004 17:01 UTC (Thu) by subscriber cdmiller [Link]

We have used qmail for about 6 years now. It's rock solid, secure, and easy to configure. We have 16 lines of configuration in the 7 files of our qmail/control directory on the main mail server. My default exim.conf for a debian/GNU workstation has 200 lines of configuration. The postfix setup on one of our redhat servers has 76 active config lines in main.cf.

It's interesting to watch something like postfix or exim evolve alongside a fairly small and static product like qmail. The free software products in this case appear to become more complex and feature ladden over time.

My organization can't redistribute modified versions of qmail, but we don't need to. We can patch our version to our hearts content if need be, and patches are merrily produced and distributed by the community.

It would be interesting to see what the community would do with a free version of qmail. Maybe DJ Bernstein will be convinced to allow a free software fork of qmail under a different name one of these years. Even then, qmail will be hard to beat for it's ongoing record of stability, security, and ease of configuration.

it does suffer a little from supporting every OS under the sun (and the complications that are nessasary to do this)

sendmail also has a ton of features that most people don't need, but when you need them they are relativly easy to turn on.

sendmail has three different ways of configuring it

from easiest to hardest they are

1. the Sendmail INC GUI, (interprets and creates .m4 files)

2. manipulating m4 files (get compiled into .cf files)

3. manipulating .cf files

saying that sendmail is hard to administer becouse .cf files are bad is like saying that developing a compiled python program is hard becouse the resulting binary is hard to understand and change (here the three levels are python->C->machine code) only experts who are doing really strange things should ever need to manipulate the .cf files

this hasn't always been the case, back in the sendmail 5 days people were expected to work with the .cf files directly. Frankly I'm glad I'm young enough to have missed those days :-)

woah! I'd never expected this outcome.

While for me, Exim was the favourite all along (see my comment on last weeks article http://
lwn.net/Articles/196856/), postfix seems to be the obvious tool to get the recommendation. Mainly
because it's more popular, features a cleaner design (by seperating different tasks to different
processes) and has a better security record (Exim had some vulnerabilities in the old days).

For me and obviously for the reviewer, these points were less important than the obvious
advantages of exim which lie in flexibility, ease of use and raw featureset.

Still... I'm somewhat surprised to see the reviewer agree with me - usually my opinions are not the
popular ones :-)

Philip

The reason I use sendmail is that it lets me do anything I want in terms of sending mail. That's a feature I haven't found in any other MTA. For various historical reasons, I have a fairly complex mail setup, and need to route mail based on arbitrary features of the message (sender address, and even sometimes content of the message body). Sendmail lets me do that.

It just seems that the whole point of this article was to plug the author's preferred MTA, rather than provide an unbiased overview.

Disclaimer: I am just a Mail system administrator, not a developer,
and I am not familiar with the other MTA's discussed in the articles.

However I don't think anyone should be put off using Postfix because
it only has a small number of developers. A small number of _smart_
developers working in a well defined problem space can clearly
make really nice software.

As for a less predictible future, in the last 3-4 years that I have
been using Postfix, I dont remember any changes that made me think
"I wish they hadn't done that".

On the License, it doesn't bother me as a user. The code belongs
to the developers to license as they wish. If they saw it as a problem
they could always relicense it differently, but I suspect they are
happy with how things are.

I especially disliked the two remarks on how qmails code is old and
inherently unsupportable. As a matter of fact there are several companies
who support qmail commercially.

Perhaps related, I use TeX a lot which also hasn't changed in some 15
years. But I tribute that stability to the great genius behind the
system. Code doesn't suddely get 'crufty'.

Wanting minimum hassle

Life With Qmail

Needing commercial support

17 companies listed on qmail.org

Inexperienced

qmail is by far the easiest to set up. For more complicated setups other MTAs are more appropriate though.

Controversial articles have to get their facts straight to be taken seriously.