My department has an internal SMTP relay running on a Windows 2008 R2 using IIS 6 and was configured to use an external smart host and that was working fine.

Recently our IT department set up their own internal SMTP relay and wants us to utilize their SMTP server and shut down the 3rd party smart host (guessing to save money)

We have a ton of jobs and notifications that are all pointing to our existing SMTP server and I don't want to have to try and track them all down and update to the new one.

Is there a way to configure our existing SMTP to relay to the new SMTP server which will then deliver the email?

(99% of the emails are internal only and I know the one application that is sending external and I can reconfigure that manually, so this will all be internal email routing.)


Configure your SMTP server to use their SMTP server as a smarthost, just like you did with your existing smarthost. Simply remove the existing smarthost server and add theirs.

  • They only provided an IP address (internal 10. range) and when I change the Smart host value from the previous URL to the new IP, the SMTP Configuration throws a warning: "The domain name is not valid" and won't let me make the change. Would I need to potentially edit the host file to fake a URL and route it to that internal IP, or do I need to have them do something so I can make the change? – Dave Nov 22 '19 at 14:56
  • I had to put brackets around the IP address to get it to register, I'm going to make the rest of my changes and see if it works... – Dave Nov 22 '19 at 15:03
  • Yes, you need to put brackets around the ip address. – joeqwerty Nov 22 '19 at 15:17
  • Adding the brackets got it to resolve and all internal emails are now sending from our server to their server and from their server to the end user. (Externals are failing, but that's on their side to figure out) Thanks for your help! – Dave Nov 22 '19 at 15:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.