Review of Managing IMAP

Managing IMAP
Dianna Mullet and Kevin Mullet
O'Reilly & Associates

Reviewed by Nick Christenson,

March 24, 2001

As people come to increasingly rely on email services and as their sophistication with this medium rises, their demands on their email systems become more complex. The IMAP protocol, which is supported by several free and commercial email products, was designed to be the next generation feature rich client-side email protocol. However, with the increased capabilities of IMAP systems comes increased complexity in design and maintenance of their servers. This book is designed to act as a reference for email administrators who want to provide IMAP service, principally through the two most prominent Open Source server packages, Cyrus IMAP and the UW IMAP servers.

The bulk of the book is divided into five parts. The first covers IMAP fundamentals. In this chapter IMAP and POP3 are compared, the IMAP protocol is discussed, and some background material on Internet email is provided. This section is pretty good and should be useful to any email administrator trying to come to terms with what IMAP is all about.

The second section covers Mail User Agents (MUAs), the client side programs such as Outlook, Netscape, and pine, that are used by human beings to interact with IMAP servers. Information is also provided about web-based IMAP clients, which are programs that run under a web server that turn an HTTP based mail session from users into IMAP sessions with the server. While the authors cover the most popular MUAs and characterize each fairly well, I would have like to have seen more information on how each MUA interacts with each server. Unlike the POP3 protocol, the IMAP protocol is so rich that different clients can use the protocol in different ways to perform similar operations during a session. Different choices in this matter can have profound performance effects on the IMAP server. Some discussion of this would have been welcome.

The third section covers the Open Source Cyrus IMAP server. The book primarily focuses on Cyrus version 1.6.x, while the Cyrus folks at CMU are currently encouraging everyone to move to Cyrus version 2.x. At the time of this writing, this isn't a serious problem, as my recommendation for most environments would be to continue to stick with the latest version of Cyrus 1.6 for the time being, but this will soon be out of date advice. The section covers installation, configuration, and administration, and does a pretty capable job, although there's still quite a bit that can go wrong during any of these processes. However, this section can help an administrator avoid quite a few of the common pitfalls, more than one of which this reviewer has encountered personally. Section four covers the University of Washington (UW) IMAP server in much the same manner that the previous section covers Cyrus. The comparison between the two is pretty fair and enough information is presented for most administrators to be able to arrive at an informed choice as to which system better suits their needs.

Section five covers other topics including security, mail filtering, performance tuning, configuration storage, and IMAP tools. The configuration storage and tools sections are pretty good, the former will be useful for those using one of the IMAP servers the book focuses on, although in my opinion the authors are a bit too hard on LDAP for smaller sites where performance considerations are not paramount, and the latter will be useful to any IMAP email administrator. There is a great deal more that could (and should) have been said about IMAP system security, and while the performance tuning chapter covers some important issues, there is a lot that isn't said about this topic.

Although I have my quibbles, this book is a solid work on managing IMAP servers. Anyone considering supporting an UW IMAP or Cyrus installation that isn't already an IMAP server wizard will find a great deal of value in Managing IMAP, and any other IMAP administrator can almost certainly find enough of value here to make reading this book worthwhile, although the reader can safely skip those chapters that deal with IMAP servers that they're not interested in. Appendixes provide information on server conversion to Cyrus from standard Unix mailbox format, SSL support in IMAP, and a list of the IMAP command set which is basically a restatement of RFC 2060.


Overall, a very solid book on running an IMAP server. The book would be indispensable to those new to either Cyrus or UW IMAP server administration and useful to those who are either more experienced or not running either of these IMAP server packages. The book is nicely compartmentalized so that one can safely skip over topics that aren't of interest. I recommend Managing IMAP.

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