Apache: The Definitive Guide, 3rd Edition

Mailserver

Most web sites need a mailserver to keep in touch with clients and to tell people in the organization what the clients are up to.

The Unix utility Sendmail (http://www.sendmail.org) is old and comprehensive (huge, even). It had a reputation for insecurity, but it seems to have been fixed, and in recent years there have been few exploits against it. It must mean something if the O’Reilly book about it is one of the thickest they publish.^[3] It has three younger competitors:

Qmail (http://www.qmail.org)

Qmail is secure, with documentation in English, Castillian Spanish, French, Russian, Japanese and Korean, but rather restrictive and difficult to deal with, particularly since the author won’t allow anyone to redistribute modified versions, but nor will he update the package himself. This means that it can be a pretty tedious process getting qmail to do what you want.^[4]

Postfix (http://www.postfix.cs.uu.nl)

Postfix is secure and, in our experience, nice.

Exim (http://www.exim.org/)

There is also Exim from the University of Cambridge in the U.K. The home page says the following:

In style it is similar to Smail 3, but its facilities are more extensive, and in particular it has some defences against mail bombs and unsolicited junk mail in the form of options for refusing messages from particular hosts, networks, or senders. It can be installed in place of sendmail, although the configuration of exim is quite different to that of sendmail.

It is available for Unix machines under ...