I've asked this before, and I have been trying to find out what the problem is but I can't find a solution. I have just set up ISA on a standalone Server. I have published our Web, FTP, and Mail. Internally everything is working. Clients behind the ISA Server can send and receive mail, web browse etc..... without any problems. The issue that I am having, is that I am dialing up with a test machine to see if I can send and receive e-mail using a POP Client. I have an Exchange 2000 Server behind my ISA server. I can receive mail from our server, but when it is trying to connect to send, it gives "unable to connect to server". I have the smtp service published and it is running on the Exchange server. I have followed Toms' article on "ISA Server SMTP Server Support". And allowed outbound access to the smtp server port TCP 25. Do I have to allow inbound on the same port as well? Is this what I am doing wrong? Can someone please help? I've been trying to get this thing working without any success. Thank you,