When a message gets sent out to user@remotedomain.net the server looks in it’s DNS records to find where the mail server for remotedomain.net is so that it can send the message along.
Check your server’s DNS forwarders to make sure they are correct.
I had the correct DNS servers in.
Next thing to check is what IP mail.remotedomain.net is resolving to.
As you can see, the server is being told that the mail server for remotedomain.net is located at 6x.xxx.xxx.22, which is not the correct address.
Since it is not the correct address, the emails stay in the queue on the server…
The correct address can be found by looking up mail.remotedomain.net IP and DNS information. I use the website who.is but you can use whatever tool you feel like using.
From a machine outside of your network, one that is not using NTD’s DNS servers, I am able to get everything working just fine.
Here we can see that pinging mail.remotedomain.net resolves to the right IP address.
I called the ISP and explained the issue and they found that they had hosted this company’s email at some point and still had an A record in pointing to 6x.xxx.xxx.22 rather than 21.
