If you run a mail server at home you might find outbound email doesn’t go.In my case, I had AT&T DSL for years before switching to Charter for better speeds. Now if only they didn’t tack on hidden fees and drop the connection a few hours a week I might have stayed with them more than 6 months.
But I digress.
Back on AT&T I found my email would no longer send from my server. I switched to using changeip.com’s email forwarding service (aka “smart host”) in addition to their dynamic DNS service sometime back. My reason for using a smart host was blacklists- the main lists include all big lists of dynamic addresses ISPs assign to home users, meaning you can’t directly send email from a dynamic address to any email server referencing a blacklist (which is pretty much all of them).
My initial solution was to use AT&T’s email servers as smarthosts, but I found that often failed for AT&T-family email (email to Yahoo addresses would fail about 10% of the time). So I added a couple bucks a year to my ChangeIP account and route all outbound email from home through them.
This worked fine until I switched back from Charter and found AT&T was blocking port 25. Now, I don’t think this is a recent change and have no idea why it worked fine 6 months ago.
The solution is to have your smarthost receive email on an alternate port.
To setup the smarthost in Exchange 2007 or Exchange 2010 launch the management console and open “Organization” then select “Hub transport”
Click the “Send Connectors” tab and open the properties of your send connector.
Select the Network tab
Choose the radio button for “Route mail through the following smart hosts:” then click “Add…”
Enter the IP address or FQDN (smtp.changeip.com) then “OK”
Your smart host probably requires authentication (normally your email address and password) so click the Change button, choose Basic Authentication and enter your credentials. Your provider will let you know if you need other options (ie TLS).
Setting the port can’t be done through the GUI. Open the Exchange Management Shell and Run this command, replacing my Send Connector name with yours and your providers alternate port with Change IP’s “5072”.
set-sendconnector “Outbound SMTP” -Port 5072
I tried looking up AT&Ts settings but their support site is down at the time of this writing.