Hi all, I've the following scenario: server_a Exchange 2003 with some mailbox server_b Exchange 2010 with some mailbox server_c Exchange 2010 with the role of Hub Transport In the AD there is a universal group called "all_users" wich contains other groups (all universal) and in this way this "super group" contains all the users. When a user that has the mailbox on server_a try to send a message to the group "all_users" the message is not delivered to all users, certain users do not receive the message. With the tracking of the server_a I see that it tries to deliver the message first locally (and all the attempt are successful) and the tries to deliver the message remotely to the server_b. With the tracking of server_b or server_c I don't see the message either if i set as recipients the "all_user" or those users that do not receive the message.

Hi Server a works well. So you can’t get NDR. According to your experience, some users or distribution group can’t be sent cause this kind of problem. If I were you, I would do many tests to find the problem. 1. Can you send email to one user on exchange 2003 by this user? If it doesn’t work, please check exchange 2003 send and receive connecter. 2. If it works, Can you send email to group which contains all users on exchange 2003 by this user? If it doesn’t work, please check distribution group on exchange 2003. 3. If it works, Can you send email to one user on exchange 2010 by this user? If it doesn’t work, it is problem between exchange 2003 and exchange 2010. Please read these three articles. http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/5466a0ba-f59a-4cfa-ba41-b66b249b955d http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/856fbdf5-9c5a-436e-8ddf-484d995be4ac http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/81f02c81-1975-4366-bafc-2c7028755f9b/ 4. If it works, Can you send email to group which contains all users on exchange 2010 by this user? If it doesn’t work, please check distribution group on exchange 2010 and post event error. It is very complex problem. 5. If it works, Can you send email to group which contains last two groups by this user?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.