OpenVISP is a big project for Virtual ISP admin / pannel tools. You can see
some primilary info on the OpenVISP tools
You will find there projects :
PopDrop is a POP3 to SMTP redirector like Fetchmail is.
It is written 100% in Pike and it is designed to run with thousands of accounts
in a MySQL Database.
It is threaded and it is designed to be fast.
Download the lastest version (1.9).