We're testing moving user mailboxes from Exchange 2003 to Exchange 2007. Once we move users' mailboxes over, they can no longer send from Outlook. Here's the error they see in Outlook 2010: You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission. Please help!

How are you moving these mailboxes? Are both servers in the same Exchange organization? -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "mikeerter" wrote in message news:f649cd00-1143-4dc5-a86f-61390db35301... We're testing moving user mailboxes from Exchange 2003 to Exchange 2007. Once we move users' mailboxes over, they can no longer send from Outlook. Here's the error they see in Outlook 2010: You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission. Please help! Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi Ed, Same Org. I moved one with the move-mailbox cmdlet and the other using Exchange Management Console. One hunch is that the accounts are both members of Domain Admins... but I'm not sure it that matters. The moved mailboxes can send from OWA too- just not from Outlook. Mike

Yeah, in fact that matters. Exchange 2007 and 2010 blocks mail access to accounts in protected groups. You'd better start observing best practices and create separate non-mailbox-enabled administrative accounts. -- Ed Crowley MVP "There are seldom good technological solutions to behavioral problems." . "mikeerter" wrote in message news:53120487-4e29-46d9-a417-4a3a4a12f064... Hi Ed, Same Org. I moved one with the move-mailbox cmdlet and the other using Exchange Management Console. One hunch is that the accounts are both members of Domain Admins... but I'm not sure it that matters. The moved mailboxes can send from OWA too- just not from Outlook. Mike Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Does this have to do with AdminSDHolder? Can you be a little more specific and perhaps point to some documentation? Thanks a lot! And I agree with your point about best practices.

This appears to be the answer: http://support.microsoft.com/kb/907434/en-us