Exim & Postfix flexibility [LWN.net]

Exim & Postfix flexibility

Posted Aug 24, 2006 18:33 UTC (Thu) by rfunk (subscriber, #4054)
In reply to: I just love Exim by pilif
Parent article: A comparison of Mail Transfer Agents - Part One

When I was last looking at postfix, it treated SQL-Users as aliases which had to be mapped to some "real" users.

Must've been before virtual support.

What you were looking for sounds a lot like what I implemented with Postfix and Postfix Admin (as well as dovecot).

I used to like Exim for its simplicity and power, but Postfix has matured quite a bit over the years, so at this point I see Exim as powerful but complex, while Postfix gets the points for simplicity and power.

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Exim & Postfix flexibility

Posted Aug 24, 2006 18:57 UTC (Thu) by Alan_Hicks (subscriber, #20469) [Link]

I concur. You really can't go wrong with either, but postfix has made some significant progress over the years. It used to be that if you wanted to do anything fancy, you had to use sendmail (or later exim) and the configuration was terribly hard. MTAs are one of those things that are constantly changing though, and postfix has grown up a lot since the grand-parent last seriously evaluated it.

Today postfix has excellent virtual user support and supports just about every authentication mechanism you would want. As for the article itself, the writer mentions that postfix docs are "scattered" around. I can't say that I've ever had a problem finding documentation for postfix, and what I do find is hands-down some of the best documentation I've ever seen for free software. The man pages are excellent (every bit as good as you would expect from the BSD world) and the txt and html docs included with the source code will walk you through just about everything.

For good dead trees documentation and an overview of how to do things with postfix, I found the O'Reilly book "Postfix - The Definitive Guide" by Kyle D. Dent to be excellent.

Exim & Postfix flexibility

Posted Aug 25, 2006 8:27 UTC (Fri) by kleptog (subscriber, #1183) [Link]

The thing that annoys me about Postfix while looking at the config file is that it's a lot of options, but from those options I have no idea how the system actually works. With Exim the config file describes the process taken to deliver a mail, from beginning to end. Take for example processing of the .forward file.

In Exim there's a director down the end that specifies the filename and how to handle it (permissions, user, etc). So I know where in the mail delivery process it appears. I can ask for it to check for the .forward files in a central directory, or check in a database if the user is allowed a .forward file. The default postfix configuration doesn't seem to mention the .forward file at all.

If someone comes along wanting special mail routing for domain X, I can just add a stanza matching that domain and add the rules. I can decide if it comes before or after the virtual tables, or anything else.

Maybe postfix can do this too, but from looking at the config file I certainly don't get that impression. It seems to be full of implicit rules, and I hate that.

Exim & Postfix flexibility

Posted Aug 25, 2006 8:59 UTC (Fri) by ahoh (guest, #17291) [Link]

When I was new to Postfix (that was at a time when the postgresql patch
was a brand new thing) I found the online documentation very helpful. And
it still is.

Don't bother too much with the comments in the config files (they are only
comments after all, usually only focusing on a very specifiy aspect). They
are helpful if you have allready some routine in running Postfix.

Have a look at http://www.postfix.org/documentation.html and dig through
the problem you want to solve there. I bet most of what you want to
configure is described there with the big picture and an overview of all
the corner cases it touches.

Postfix uses more then one file and several databases. That IS different
from a single config file to catch all.

Exim & Postfix flexibility

Posted Aug 25, 2006 18:15 UTC (Fri) by tsr2 (subscriber, #4293) [Link]

If there's a solution there (at http://www.postfix.org/documentation.html) for what I wanted to do with an MTA, it was far from obvious. The solution was relatively easy to find in the Exim documentation, so I went with Exim. IMHO the Exim documentation is significantly easier to use.

As someone who had never set up a proper MTA before, I was quite happy to set up Exim for my work, based on the available documentation, whereas I would not have been happy to do the same with postfix.

I can always find what I need in the Exim Specification or the FAQ, whereas I couldn't easily find what I needed in the postfix docs.

Exim & Postfix flexibility

Posted Aug 25, 2006 12:14 UTC (Fri) by rfunk (subscriber, #4054) [Link]

I like the fact that Postfix doesn't need everything in the config file,
just the stuff different from the default. It keeps simple
configurations simple. That's why I consider Exim and Sendmail to be
more complex to configure.

If you want a config file with *everything*, run the postconf command.
It shows the complete current configuration.