Here I answer the questions which I got from users. If you don't find an answer feel free to contact me
Q: Why MySQL and not LDAP?
A: Good question. LDAP is role-based and it would be indeed a better solution for such applications. Unfortunately LDAP is very hard to set up. You have to make proper schemes etc. MySQL is the way strait ahead, it is very easy to handle and versatile. There is a PAM module available for LDAP, feel free to use it.
Q: Why Postfix and not Qmail?
A: Lots of people like to see such a setup with Qmail. The reason why is, Mysql-support is a hack and not in the included in the main source-tree. This could end up in a bad situation. Think if a security-hole is found in qmail and the patch does not work with the corrected version. Postfix is supporting MySQL natively. Another (personal) reason is that I find Postfix more sympatic (I don't know why)
Q: I got a Error: "Temporary lookup failure"
A: Postfix cannot look up the alias table. Must common failure is that MySQL is not running, or there is a authentication Error. Check /var/log/mail and /usr/local/mysql/var/<hostname>.err to track the error
Q: Does this HOWTO also work on other platforms?
A: Unsure. I personally compiled MySQL and Apache on AIX 4.3 and 5.1L (php does not run properly on AIX), Solaris 6/7/8 and HP-UX. Cyrus, pam_mysql and cyrus I never tried. On Solaris there is maybe a chance to get pam_mysql running. On AIX there is no PAM, but a similar mechanism. In short: Try it, and let me know if were successful