I'm trying to set the display name of the sender on an e-mail. I have tried to set both the Sender and From attributes of the EmailMessage but neither seem to change the display name - the e-mail always arrives with the actual name associated with the Exchange account.
Is there a way to successfully change the name that is displayed without changing the name of the account or changing to another account?
No when the message arrives in the Target Mailbox the Information store will resolve the Address back to the Native (EX) Address of the recipient which will mean if you look at the address in the Client it will always appear as the primary. This is the way Exchange has always worked and can't be controlled.