I administer an SBS 2003 SP2 Exchange server for a client. I have set up 3rd party spam filtering. They use a Sonicwall firewall and would like to block all IPs to port 25 except a range provided by the 3rd party. I have done this, the problem is that the client has several employees that use outlook and outlook express pop mail from home and it gets blocked. As much as I’d like them to switch to OWA they won’t do it. I can’t open the firewall to their IPs to allow their email from home as they are not static and it’d be an administrative nightmare. Is there a way to use a different public IP at the client site to accept port 25 from these clients and then connect that to the exchange server? Or what about using port 456 on pop clients rather than port 25? Can either of these be done? Is there an easier way to set this up? Thanks for any help.