Comment by chrislomax

It stops our mail server from being used as an open relay though?

How does blocking 1 specific port stop the issue anyway? They can just change the port they connect on?

As stated in the actual article...

Do these government agencies actually think blocking port 25 will reduce spam? Most of the issues stem from open relays.

I was offering an opinion on how to resolve those issues. Changing which port accepts the mail is in my opinion pointless.

It's like saying that most burglars come in through the back door so the government blocks everyones back door, they will just come in the front.