I have the following set up. Exchange server 2003 on windows 2003 on the internal LAN sitting behind an isa server 2000 on windows 2003. It is a stand alone isa server acting as our firewall and connects to our ADSL router. I use this route to the internet successfully for inbound and outbound http traffic but when I try to receive incoming smtp traffic emails don't arrive. On the isa server I have disabled the smtp filter and tested by using the mail security wizard to publish the exchange server as well as tested configuring the isa server as a smtp relay and neither work.
Please can you advise on where I am going wrong???
Many thanks in advance