I have been really beating my head against on the wall on this one, maybe someone here can help:We have an Exchange 2003 server with approximately30internal users on the local network. They connect usingthe Exchange server protocol, using Outlook 2000 in most cases. This works fine and continues to work correctly. We also have an external office located in another state. There are 3 computers there using Outlook 2007. I want to connect their Outlook installations to our Exchange server. First, I set up POP3 connectivity. This allows the 3 users to receive their email from the main server. Unfortunately, SMTP does not work. This is the reason why:- We use an external email filtering solution (MessageLabs)for SPAM and viruses. All of our incoming email is routed through their servers, then sent on to our main server.-MessageLabs connectsto our SMTP server via anonymous access - they cannot use authentication. I have verified this already.- Because of this, our firewall ONLY accepts SMTP port 25 traffic from the range of IPs that MessageLabs provides us.This ensures that the only anonymous SMTP connections are those coming from MessageLabs.Due to this slightly unique requirement, is there a way I can connect the external users to our main server for SMTP? When I opened up port 25 traffic, my users were able to connect externally just fine. Unfortunately, this broke the MessageLabs filtering. It seems I'm in a catch 22.

I'm looking for a good solution to allow my remote users to connect to my SMTP server. If port 20 only allows traffic from MessageLabs, is there another protocol or something I should be looking for?

Hi,Why not deploy RPC Over HTTP in Exchange 2003?It is a good method to make the remote user connect Exchange server easily.http://technet.microsoft.com/en-us/library/aa998950(EXCHG.65).aspxOf course, if port 20 is allowed from MessageLabs, we can set the receiving port of SMTP virtual server as 20, and change SMTP oftheremote Outlook on the clientto 20.To change the port of SMTP virtual server:1, Right click Default SMTP Virtual Server, select Properties, click Advanced tab, click Edit button, change the TCP port as 20.ThanksAllen