I have just created and new Outlook profile in an attempt to fix an issue with view settings not being saved, since then send-on-behalf-of only works in non-cached mode. Send-on-behalf-of perms were set on the server side and have been in place for years.
When I attempt to send-on-behalf-of "LICHelpdesk" to "KCLing" in cached mode it fails with an NDR implying that I was trying to send-on-behalf-of "KC Ling" and not the "LIChelpdesk" mailbox:
Delivery has failed to these recipients or groups:
You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission. If the problem continues, please contact your helpdesk.
The sent mail copy is also odd in that it states:
LIC Helpdesk on behalf of LIC Helpdesk
<my name> on behalf of LIC Helpdesk.
Any ideas where to go on this?
I tried deleting and recreating the OST file.