Forum Discussion
Shared mailbox: Use send-as, not send on behalf from Outlook 2016
The behavior depends on how you've added the shared mailbox in Outlook (automapped vs additional account), and of course by the method you use to compose the message. Check my ramblings on the topic here: https://www.michev.info/Blog/Post/1430/
Tom Glorieux I was trying to get this work using various fixes on forums for a good few hours before I managed to get it to work.
As many people have already stated in online forums, when you remove the address from the "From" list in outlook and then reselect it from the "Global Address List" it works fine for one email, but subsequent emails fail to send.
For some reason, the Outlook desktop client must use the "offline global address list" by default even after you change it.
The fix for us was fairly simple in the end:
1. Go to "Send/Receive" tab and select "Send/Receive Groups"
2. Click "Download Address Book"
3. Ensure the choose address book field says "\Offline Global Address List" and click OK.
Once the download has finished, the emails sent as the correct mailbox every single time. I have no real clue as to why this would be the case, but I'm guessing it updates the permission list on the mailboxes for the outlook client?
But it worked!