You can download Mail Admin here - http://www.mailadmin.home21.org/versions/mailadmin.1.1.tgz
Was tested with based on exim MTA and MySQL database mail system.
Works under FreeBSD 6.0 with apache 2.2 http server and php 5.0. Will work with other apache and php versions.
How to setup mail system with virtual users described here - http://www.opennet.ru/docs/RUS/exit_setup/index.html.(Russian language only). The article became slightly out of date, but main ideas are right.
User-defined variables were located in file variables.php.
How to set apache server to work with MySQL and php you may find on their home pages.
For simple security you can use apache features. Below is example of .htaccess file.
.htaccess
AuthName ProtectedZone
AuthType Basic
AuthUserFile /path/to/.htpasswd
You need to put .htaccess file in the same directory with mailadmin script. And .htpasswd file, which you can create by using htpasswd utility, you need to put somewhere upper than accessed from http directories.
Questions, opinions and suggestions please send to my mail address peter(@)home21.org
Current version - 1.1. Features to work with domain list added - list, create and delete.
In variables file variables.php variable domaintable_status added.