Exchange 2003 - How do I block external email addresses from being able to send an email to an internal email address?

I have set up a distribution group for internal use. I dont want any external addresses (hotmail etc) to be able to send emails to the group. It should be used for internal purposes only.
How can this be done?
Who is Participating?
peakpeakConnect With a Mentor Commented:
Disribution group Properties->Exchange General, mark From Authenticated users only
there is an option to set delivery restriction in the group properties.
if you have a group which has all your internal users as members, then you can configure this new group to only accept messages from that group.
another option would be to remove the smtp address from this group's email properties and assign it a domain.local address
Assign Primary SMTP email address to this distribution group as or any other email address which does not exist and assign as seconday email address so that only internal mails will flow.
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.