Hello all, I have recently upgraded my Exchange 5.5 environment to Exchange 2003 and have one bug that is randomly appearing. We use 'shared' mailboxes for different purposes in our organization, and since the migration I have two users that are reporting that they can not 'send as' the mailbox. These reports are from two different users regarding two separate mailboxes. Both users have 'Full Mailbox Access' to the account. There are other users with the 'Full Mailbox Access' permissions to the same shared mailboxes and all of them are able to 'send as' that mailbox. What could be preventing these users from sending as the mailbox? My steps so far: 1. Removed and re-added the mailbox to their profile - no joy 2. I added a separate Outlook profile, under the user's login, as the Shared Mailbox. The users are able to 'send as' the mailbox (weird that it works this way but not when added to their profile) 3. I have removed their permissions and then re-assigned them to the mailbox - no joy 4. They have similar permissions on other shared mailboxes and are able to send as those... This indicates nothing is wrong with the User's domain account. Very weird issue... And like I said it is rarely occurring (over 300 shared mailboxes in our site). Any troubleshooting tips are MUCH APPRECIATED. Thanks, Chris