Hi,

We have a Backup Server on Azure and on time of installation we had to ask permission to Microsoft throught Azure Support to Open port 25, we had to sign a declaration taking the full responsability for it and the correct use of Port 25.

You have to contact Azure Support and see what is needed to Open 25 Port.

Hi Bill! I have had this same issue with Azure in the past. In my case, they refused to open port 25 no matter what. Since that was the case, I had to go with another server host which allowed 25. If AWS refuses to open 25, for you for any reason, please let me know and I will refer you to a host that will allow it.

I had another thought on this. Since I am only using the cloud server for backup and it will only send email to my on prem primary server, could I set up a VPN and force the cloud backup server to push all of the SMTP port 25 traffic through the VPN to my primary server? A private VPN should not have the same restrictions as a public internet port. Is there a way to set up the backup server to do this?

Hi Bill, but you also need Port 25 to receive outside emails. That's not a solution.

Thanks Kyle Kerst. I was able to get the port 25 restriction removed on my AWS EC2 instance following the link that you posted.