SendAs in Outlook client

Occasional Contributor

SendAs is not working in Outlook 2016 client. SendAs permission has been correctly assigned to users.


We used to be able to just choose the shared mailbox in FROM drop-down, but now it's sending the email ON BEHALF of the mailbox, which will fail because SendonBehalf permission is not assigned to the user. 


Anyone also having this issue?

2 Replies

What method Outlook tries to use depends on several factors, most importantly is the other mailbox added to the profile. There's a comparisson table here:


I've also put some notes here:


Assuming you are using the correct combination, clear the From "cache" and select the mailbox directly from the GAL.

That's an interesting read. Thanks.