Exchange 2007 - sending out 25 blocked somehow?

Since, I'm using an ISP that blocks incoming ports like 80 and 25, etc., I have to work things a little differently. A friend of mine has a small datacenter and he's allowed me to use his SMTP server as a relay as well as his ISA server for proxying. So, for OWA, my ISA rule is pretty much a default Exchange OWA rule out-of-the-box with the only exception being that it's bridged on the back of the rule to port 81 on my router. Then my router forwards all port 81 traffic to my Exchange server.

Now, for some reason, my ISP also blocks port 25 in and out. Ugh,... I know... a total P.I.T.A.!!!

So, what do I do?

I run all my email through my buddy's SMTP server and Exchange via not just port 25 but also port 26. So, his router forwards all traffic from port 25 to 26 to his SMTP server (just a basic SMTP server and not an Exchange server).

So, as long as your recieving smtp server (in my case, my friend's SMTP server out there on the internet) is configured to recieve from you and it's an smtp server you control outside your network, you can fix this issue.

First - make sure your external smtp server can recieve on both port 25 and 26. And that it will allow relay of your public IP along with the domain name your using.

Then in your exchange server, set your send connector's smart-host to the public ip of that smtp server out there.

There isn't an option in the Exchange MMC to use another port other than 25. So, we will need to use the exchange shell command below:

set-sendconnector -identity "yourwackyconnectorname" -port 26

This will allow your exchange box to send your emails out on port 26 instead of port 25