I see you have blocket incoming requests on port 25 for dynamic IP customers.

http://www.neowin.net/comments.php?id=7391&category=main#comments

This is, in adition to refusing your budget users a static IP, destroying the Internets intended end-to-end address transparency. A dynamic IP is barely acceptable, but blocking a port is severly breaking the connection and one cannot call it a real "internet connection" anymore.

Please read up on how Dynamic IPs, blocking of ports and forcing NAT "solutions" on end-users breaks the way the Internet was intended to be. Please consider giving your costumers a static IP, and any extra IPs they need for a small one-time fee. A well structured organization will be able to do this for a small amount.