You have an Exchange 2010 user mailbox with several email addresses assigned to it, and you need to use the Set as Reply feature.
This can be done in EMC.
- In EMC, open the user mailbox and then go to the E-Mail Addresses tab.
- You will notice that the Set as Reply is probably grayed out even if you have multiple email addresses (aliases) assigned to the user mailbox.
- Disable (deselect) “Automatically update e-mail addresses based on -email address policy”, which is on the same screen.
- Click on the desired email address.
- Click Set as Reply.
- Click Ok.