User has access to own mailbox and additional email. Call it mailbox A.
User has profile set up to access mailbox A as main mailbox. They have full access and send as permission to mailbox A.
This worked fine beforee both mailbozes were migrated today.
Now user can access mailbox A but gets an error when trying to send as mailbox A. Checked permissions and they still have full access and send as permissions. I've even removed and re-added.
Still the same. Is it something to do with the way 2013 interprets permissions?