After many years bashing my head against sendmail in all it's gory details I had amassed a fair amount of knowledge and documentation on handling the Mail Transfer Agent (MTA) in Linux and Mac OS X. This caused a fair amount of teeth gnashing when I discovered it had gone the way of all flesh in OS X Panther to be replaced with Postfix.
Fortunately, my first needs were simple and I came to realise that Postfix was a much easier system to install and maintain. Now that my needs are more complex, I was glad when this book hit my desk at exactly the same time as I started upgrading the corporate servers from Mac OS 9 to OS X Server.
Postfix: The Definitive Guide seems to fit the bill. It is a well-written and well-constructed guide to mail systems in general and Postfix in particular.
The book starts with a good overview of the underlying technology in Chapters 1 and 2. I can't blame Dent for my slight confusion in the section on addresses and headers - having RFC822 superseded by RFC2822 was just a little too much coincidence for this particular "bear of little brain." He then follows it with a chapter discussing Postfix's architecture, important since Postfix uses a much more modular approach than the sendmail monolith, with each part of the mail handling process a different executable and the single queue turned into five.
Once the background is well covered, Dent then gets onto the nitty-gritty of configuring and administering Postfix. He has certainly covered everything I needed, including spam handling, multiple domains, relaying, SASL authentication and using LDAP. Once I'd finished grokking all that, and getting it integrated into my servers, I had a corporate email system up in three sites that replaced and improved upon a couple of thousand dollars worth of proprietary dreck. Happy is an understatement.
Dent's writing is sometimes a little patchy, though never bad. The technical detail does seem overpowering in places, though, and I occasionally found myself reading a section through more than once with a configuration file open in front of me. There are certainly spots where a little more hand holding and care with the writing would have been appreciated. (If you are a little more cognizant of the interstices of mail systems then you may not have the same problem.)
I did, however, appreciate the appendices enormously. The four appendices cover configuration parameters, Postfix commands, installation, and an FAQ. My system came with Postfix compiled and installed just as I required it so I didn't get a chance to thoroughly test out Dent's installation procedure (though it looks good); the other three continue to be useful.
If you want to have a look for yourself, then the usual O'Reilly page is complete with a table of contents and index, but this time no example chapter is provided (how come, O'Reilly?). You can also get an expanded version of the FAQ in Appendix 4 from Dent's website. A better example of Dent's writing style is an excellent article on troubleshooting with Postfix logs at O'Reilly's Onlamp.com.
This is a good book, Dent has explained the underlying methodology and use of Postfix well, taken the reader through all aspects of this MTA system and explained both the why and the how. I would recommend this book (and, as a result Postfix) to anyone looking for an MTA and a guide to configuring and running it.
