How do I make an Exchange 2007 distribution list accept external emails?

Question

We've created the list and verified that it works for emails sent to the list from within the organization. But emails sent from outside addresses are ignored with no NDR. I'm guessing this is something simple...

Answer 1

By default, Exchange 2007 only allows authenticated users to email distribution lists. To change this:

• Open the Exchange 2007 Management Console
• Expand Recipient Configuration, then Distribution Group
• Open Properties of the group in question
• Choose the Mail Flow Settings tab
• Select "Message Delivery Restrictions" and hit Properties
• Uncheck the "require that all senders are authenticated"

You can also restrict/allow senders more granularly if you like.

Answer 2

Yes it is. Exchange 2007 changed the default so that Distribution Lists can only be used by Authenticated Users. If you go into Exchange Console and the distribution group, head into Delivery Options. You'll see the "authenticated users only" box checked. Clear that box, and external users can then use it.

Answer 3

My reference is 2003, so this may not be correct but ...

• is the email address "listname@domain.com" in the email field on the General tab of the properties?
• Is there an SMTP entry for it on the E-mail Addresses tab?
• On the Exchange General tab there is a Message Restrictions setting, which may be set to accept messages from Authenticated Users only.