Email servers, also called Mail Transfer Agents (MTAs), today do much of the heavy lifting required to transport email from sender to recipient, ideally without the sender or recipient being particularly aware of them. They store (queue) incoming email, then forward it to user's mailboxes, sometimes via other email servers, while often trying to avoid accepting or sending out spam or viruses. They also allow users to read email waiting for them in their mailboxes. qmail is a popular email server for Unix-based systems; "Qmail Quickstarter: Install, Set Up, and Run your own Email Server" introduces the reader to qmail as an email-delivery architecture that provides the building blocks for an email server.
Written for those who like to try installing and running software as they read, as well as for those who prefer to learn concepts first, "Qmail Quickstarter" starts out (in Chapter 1) by describing how to install and configure a minimal qmail system, introducing the reader to some popular add-ons and patches. It then delves into the qmail architecture — its modularity and inherent resistance to exploits that might otherwise impact its security, material that even Windows-only sysadmins and network security analysts might find particularly enlightening.
Chapters 2 and 3 do a superb job describing how email is injected into, and exits from, the qmail queue, including some of the protocols involved (mainly SMTP). Chapter 3 also introduces qmail's conception of a "user" (an entity that controls incoming email delivery for a particular email address or for an entire domain).
Email storage formats, and many related issues, are well-covered in Chapter 4, which goes on to introduce the POP3 and IMAP protocols (which enable manipulating emails already stored in on-disk recipient mailboxes), used by Mail User Agents (MUAs) such as Microsoft Office Outlook and Ximian's Evolution, and web-browser-based email access.
Chapter 5 covers virtualization (usually, this means multiple domain names served by a single server), introducing vpopmail and VMailMgr, two add-on packages used in many qmail installations.
Anti-spam and anti-virus measures are the focus in Chapter 6's coverage of filtering. Reasonably thorough, this is nevertheless the chapter that I found most in need of improvement — but it is notoriously difficult to address coping with spam and viruses in a sufficiently thorough fashion. However, the material on filtering email (for whatever reasons) by patching or wrapping qmail is more than adequate.
Encrypting mail transport, handling mailing lists, and an introduction to general administration of a qmail server are well-covered in Chapters 7 and 8; whereas the book's Index could stand some improvement.
Overall, this book is reasonably up-to-date on qmail, frank about many (though not all) controversial issues surrounding it, well-organized, and mostly well-written and concise. I consider it a great introduction to qmail, even for people not considering using it (or Unix), mainly because it doesn't require the reader to get overly bogged down in minutiae. Coverage of the security-conscious (if not security-obsessed) architecture and design of qmail is good, without any evident criticism of other (competing) products and their corresponding security track records.
On the downside, not all sample commands or files work exactly as expected or are consistent with each other; it doesn't cover some administrative issues, like how, when, or why to stop qmail-send (or why it might refuse to die after being told to stop); it isn't a cookbook for installing and configuring qmail, although it sometimes reads like it wants to be one; and it isn't really targeted for the sysadmin who is considering installing qmail for a large, traditional base of Unix users (for examples, no coverage of redundancy or backup of email storage, and no mention of how to obtain and install man pages for daemontools and ucspi-tcp, which are not provided in the source tarballs).
This book was written by Kyle Wheeler, a frequent contributor to the qmail mailing list, and reviewed by Russell Nelson, longtime advocate of, and expert on, qmail. The publisher sent me my free copy, asking that I publish a review of it, as I've been working as a consultant in the "qmail space" for several years and have commented on qmail security and other issues on my website and elsewhere. A detailed version of this review is also available on my website.
"Qmail Quickstarter" is a good book for anyone wanting to come up to speed on qmail, whether as their email server of choice or as a means to better choose among the many email servers available. I give this book a 7 out of 10.