Hi There We have just migrated from exchange 2003 to 2010 and we have some users that are having problem sending from shared Mailboxes getting below bounce back message. Delivery has failed to these recipients or groups: someuser@gmail.com You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission. If the problem continues, please contact your helpdesk. Diagnostic information for administrators: Generating server: someuser@gmail.com #MSEXCH:MSExchangeIS:/DC=local/DC=domain:server[578:0x000004DC:0x0000001D] #SMTP# I've given the user Full Access, Send As and Send on behalf permissions to the Shared Mailbox with no luck. If I delete the offline address book from the client computer the user is able to send emails from the shared mailbox for about a day then the problem returns. Anyone know how to fix this problem? Cheers, Brett

Make sure that their accounts or the OU in which they reside are configured so that they allow inheritable permissions. If the accounts are in privileged groups like Domain Admins or Exchange Organization Admins, remove them. If you're mailbox-enabling administrative accounts, now's a good time to adhere to best practice and use separate accounts for administration and routine work.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

We already separate admin accounts and standard account. Also the users account has already been set to allow inheritable permissions.

Are you trying to send on behalf of a gmail.com user? Did you do an upgrade within the same organization from Exchange 2003 to 2010 or did you create a new forest and organization?Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

The upgrade was done within the same domain.

Your OAB may be corrupt/not updated, try rebuilding this and test, Also, if you select the actual shared mailbox from the address list rather than GAL does the issue still remain?Sukh

Re-build OAB and restarted Exchange file Distribution and System Attendant services. I also change the internal OAB url from http to https this seem to have resolved the problem.

Looks like this has only temporary resolved the problem. The problem reoccurred after about a day or two.

Hi Brett, Could you please test it using OWA, any issue? And other tips for you troublshoot the issue: 1. confirm the OAB is generated by the new exchange 2010 server, also confirm that the filter is converted from ladp to opath 2. confirm the proper OAB is set as the default, and it contains the proper following address lists 3. you also could make a test to create OAB including only \GAL; and then update the OAB using update-offlineaddressbook, and then run get-clientaccessserver | update-filedistributionservice; and then run set-mailboxdatabase for the database with the new OAB Regards!Gavin TechNet Community Support