I've got a user who I need multiple other users to have "Send As" to. This has been setup and working. However, after the DST patch and the security roll up on exchnage it quit. So i've given the users full mailbox access and given them send as in the security tab as well. Then I also went to the advanced security and gave them send as for "this object only". They still get the error that they don't have access to send on behalf of the user. So i created a test user. Set that user up exactly like the other. Same OU, same groups, same access to the users mailbox to "send as". Works just fine for the test user but still doesn't work for the others. Any ideas?