Your message wasn't delivered because of security policies in Exchange 2007

Issue: Your message wasn't delivered because of security policies in Exchange 2007

Synopsis: When a user tries to send an email to a distribution group, this error maybe returned: delivery

has failed to these recipients or distribution lists. Your message wasn't delivered because of security policies in Exchange 2007

Cause: This can occur if customer/user tries to email a distribution list from outside the institution to an internal distribution list. By default only authenticated users are allowed to email a distribution list

Resolution: To allow emailing to the distribution group from outside your organization, follow these steps:

1. Open the Exchange Management Console

2. Expand Recipient Configuration

3. Click Distribution Group

4. Double click the distribution group

5. Select the Mail Flow Settings Tab

6. Double click Message Delivery Restrictions

7. Uncheck "Require that all senders are authenticated"

8. Click OK

Settings are immediately effective ,so it should work right away.