Chapter 1. Basic Qmail

If you're diving into this section, chances are you're either entirely new to qmail, or you're looking to get a feel of this book. There are many very good qmail installation guides and tutorials that are available for free on the Internet. The current version of qmail was published on June 15th, 1998. Since then what has changed the most about the qmail experience is the accumulation of expertise and experience in using and tailoring it for the most common situations and even some uncommon ones.

Without delving into the architecture, qmail is extremely modular. In many ways, qmail is less of a mail server and more of mail server architecture. Pieces of qmail can be replaced, rearranged, filtered, and extended as necessary to achieve virtually any feature the administrator desires. However, along the same lines, qmail requires certain assistance to provide some features one ordinarily expects. Qmail's SMTP server, for example, cannot talk to the network by itself; this ability is provided by software like inetd or tcpserver or similar. This design makes qmail's components secure and much simpler and easier to verify. This design also makes the details of how the qmail components are hooked together a vital part of the system configuration, as opposed to a single monolithic server with a complex configuration file that can achieve the same thing.