Exchange 2016 Distribution Group doesn't work for external email

David XF
David XF used Ask the Experts™
on
I have a client with a new Exchange 2016 server.  We setup a Distribution Group.  Email sent internally to the Distribution Group are forwarded as expected.  Email sent externally to the Distribution Group are never sent.  Distribution Group is working for internal email addresses but not external email addresses.

I reviewed Delivery Management for the Distribution Group.  "Senders inside and outside of my organization" is selected.  There are no restrictions setup - "All senders can send messages to this group".  Nothing is setup in Message Approval - no boxes are checked.  What am I missing?  Is there a global setting somewhere that's overriding the Distribution Group settings?
Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
Are you sure your external users are emailing the correct smtp address for that distribution group.  When an external sender sends an email what error do they get?
David XFSystems Administrator

Author

Commented:
Positive the external senders are using the correct address.  Copy and pasted into Outlook.
External senders are not receiving any errors or alerts.  Email is just not sent.  Exchange is acting as if "Only senders inside my organization" is selected, but it's not.
FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
The distribution list was set up as a Universal Group, correct?
David XFSystems Administrator

Author

Commented:
Yes.  It's setup in AD as a Universal Distribution Group.
FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
Send another email in to the DL and check your message tracking simultaneously.
David XFSystems Administrator

Author

Commented:
I may need some help with the message tracking.  I'm used to using Message Tracking and Tracking Log Explorer in Exchange 2010.  I'm not seeing either of those in Exchange 2016.  Are they hidden somewhere?
Active Directory/Exchange Engineer
Top Expert 2015
Commented:
In Exchange Admin go to Delivery Reports

ref link:  https://technet.microsoft.com/en-us/library/bb124375(v=exchg.160).aspx
☁ François Peroux ☁Cloud Security Consultant
Commented:
Hello,

You can find tracking in the Delivery Report EAC console, just under Mail Flow > Delivery Reports.
David XFSystems Administrator

Author

Commented:
Thanks for the help.  I'm being pulled offsite for the rest of the day, so I'll continue working on this issue tomorrow morning.
FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
ok
David XFSystems Administrator

Author

Commented:
First, the Delivery Reports in the EAC are worthless.  I just taught myself how to pull logs using get-messagetrackinglog in the management shell and was able to get information that actually helps.

It seems the problem has nothing to do with external email sending to a distribution group.  The problem is that the distribution group contains external email addresses.  If an external email sends to the distribution group, internal users that are part of the distribution group receive the email, external users that are part of the distribution group do not receive the email.

It looks like an issue with our Exchange and Barracuda Spam Filter?  (We route all email through Barracuda).

ConnectorId             : Barracuda Send Connector
Source                  : SMTP
EventId                 : DEFER
Recipients              : {xxxxxx@external.com}
RecipientStatus         : {451 domain not found (not relaying for xxx.xxx.xxx.xxx)}
FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
Set up those external email addresses as contacts of your Exchange and them to the distribution group and see if the external emails addresses get the emails
David XFSystems Administrator

Author

Commented:
Already done.  The external users in the distribution group are already setup as Contacts in Exchange.
☁ François Peroux ☁Cloud Security Consultant

Commented:
Or if there is too many contacts, you can create a new connector from your organization to a partner organization. You include the different domains of the different companies you have in your distribution groups.

Let me know !
David XFSystems Administrator

Author

Commented:
Turns out this was an issue with the configuration of the Barracuda spam filter. Thanks for the information on message tracking in 2016 - that led to the solution.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial