Outlook reply to e-mail problems

When I try to reply to an e-mail in Outlook, (not outlook xpress), in the To: field it only dispays the name associated with the return address.
Example:
To: John Doe
CC:
Subject: Whatever

And the mail is returned undeliverable, I can right click on the name and click properties to get the e-mail address, copy, paste, and then send successfully…

Any help would be greatly appreciated…