Post.Office : Administration : Restricting Mail Relay
I am having trouble figuring out the "Restrict Mail Relaying" System Configuration page. What does all of that mean?
Although Post.Office ships as closed relay, it is important to know what the settings on this page are for in case you plan on making changes. The Administration Guide goes into detail about the functions of each field, but this page should give some general guidelines to follow.
Here is an example of the page with some comments: