We have some products that generate unauthenticated e-mails that need to go to internal users who are not allowed to receive e-mail from outside of our organization. Typically the way to block some users from receiving e-mail from the outside is to only allow e-mail from authenticated users. If we take off the authenticated users only restriction they can receive these e-mails but then they get all of the outside e-mail as well.
I already use a distribution list and a transport rule to keep these users from sending e-mail to the outside. I tried creating Transport Rules to block members of the internal e-mail only distribution group from receiving e-mail from outside the organization so I could allow unauthenticated internal e-mail but it doesn't appear to work. Is there a way to do what I need to do?