SitePOP:
http://www.yourdomain.com/cgi-bin/sitepop
This script allows each domain to manage their POP3 accounts on your server. It will let you add, delete or modify POP3 accounts in real-time using nothing more than your web browser. Note each domain's owner must first FTP into their site and remove the file called "sitepop_pwd" that is in the root of their domain. This prevents others from going to their IP address before they have a chance and logging in. Once the file is removed they may enter a new password and username into the control panel, and login.