Good Morning,

We have one distribution gorup that we cant send emails from outside network. everything else is just fine. I double checked and the option 'Senders inside and outside of my organization' is selected too. 

what can be the issue with this. its a new distribution group. every other distribution group is just fine.

here is the message we get when sent emails from outside to this distribution group:

Final-Recipient: rfc822;info@mydomain.com

Action: failed

Status: 5.5.0

Diagnostic-Code: smtp;550 #5.1.0 Address rejected.

• Edited by Riaz Ansary 17 hours 21 minutes ago

What's the NDR?

Hi,

Please confirm whether the internal users can send message to this distribution group. Additionally, please make sure the email address is correct when sending message from external users.

We can send test message to this group with other external senders. If the issue happens to all external senders, please run the following command to check the distribution group settings:

Get-DistributionGroup -Identity Group1 | fl

We can compare the configurations with other groups. If there is no issue with configuration, please confirm whether there is any transport rule created to reject the external message sending to this group.

If all fails, please create a new distribution group to replace this problematic group as a workaround.

Regards,