Hello I have an Exchange 2010 and clients Windows 7 and XP.
I configured a new Domain user "user2" with a mailbox. The "user1" has to use this user2's mailbox. so in the user2's mailbox i added "send as" and "complete access" to user1.
In the outlook I add the user2's mailbox, and in the left panel tree appear a new group folder for the user2's mailbox. I f i send a mail to user2'mailbox come in the inbox folder of the new group folder( all is fine).
When i try to send a mail from email@example.com the outlook send me a message to say "can not send a message on behalf of another user unless you have permission to do so".
But i think i gave the permissions int the exchange console...