RE: [exim] Has anyone done this?

Marc wrote:
> "Why not check the sending IP to see if it can receive
> anything on port 25?" Has anyone try this?

With all the filtering rules you come up with (assuming you implement them),
I'm amazed you receive any email at all!

With a filter such as this, you'll hit many false positives as someone else
mentioned. It is quite common in large mail set-ups to have incoming and
outgoing SMTP from separate systems. Such a test would be ignoring DNS MX
records, which is what controls what system should be receiving email on
port 25. If you assume that the system sending the email must also receive
email, you'll be in for lots of fun!

Eli.