FIX: Your message wasn’t delivered because of security policies in Exchange 2007

When you’re trying to send an email to a distribution group, the following error may be returned:

Delivery has failed to these recipients or distribution lists

Your message wasn’t delivered because of security policies in Exchange 2007. Microsoft Exchange will not try to redeliver this message for you. Please provide the following diagnostic text to your system administrator.

In most cases, this error appears because you’re trying to email from outside your company to an internal distribution. By default, only authenticated users are allowed to email to a distiribution group.

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.

To create a more secure environment, it’s better to define email addresses where from mail may be sent to the distribution group. This allows you to prevent spamming from unknown email senders. To only allow email from known email senders (outside your organization), you first need to create a mail contact. To create a mail contact, go to Exchange Management Console -> Recipient Configuration -> Mail Contact , right mouse click and choose New Mail Contact.

After you have created the mail contact, do the following:

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. Select “Only senders in the following list:“
8. Click Add…
9. Select the mail contact and click OK
10. Click OK