The whole beast is still in very early stage, but it's a very active project with new exciting features added everyday. This is a patch against the Qmail mail server. It may save a lot of hard disk space and does not change anything to the POP3 nor SMTP protocols. That file maps pop logins to the path where their mails are stored, and the real UID the server should fetch them as. Logins can be different from system ones.
Passwords can differ, too.
The package contains some documentation, a script for easy installation, a program to create an initial database, and another program to easily update passwords. It was especially designed to keep you house clean with the best possible tidying organization. My wife and I use it daily for more than one year. Jean-Yves Lafesse depuis le site d'Europe 2. But nothing is more buggy than Netscape products.