We have an exchange 2003 server that 99% of the employees connect using outlook and rpc/http but one owner refuses to give up his outlook express. We have switched to having our mail routed inbound thru a symantec mail appliance and are very satisfied with its perfomance. Our problem lies in that we at this point are forced to have port 25 in our firewall open to the exchange server, which allows for spammers to still hit the exchange and flood our system with trash. One alternative is to change the public port number that routes to the exchange server to say port 2525 and route that to 25 internally and change the OE client to send on port 2525. Is there a way to force the exchange server to only accept connections from either specific ip addresses and authenticated users. THis would allow our other mail servers and the mail filter to continue communications as well as this Outlook express user.