Outlook 2010 tends to show user names, not email addresses when you look at mails. I guess they want to make mails more user friendly, by automatically converting user names to and from email addresses. You can always retrieve the real email address in the original mail, although it's a bit annoying to do: to see the entire mail header
- open the mail in separate window
- click the File Tab
- click on the Properties button in the central window pane
When you forward the mail, the receiver can do this on the mail you sent, but not on the original, included mail. Outlook strips out header information for the To: and Cc: fields in the included mail, this time mainly out of privacy concerns. When I forward a mail to a project group, I often want to forward the email addresses on the original mail as well. To do this select Forward as attachment. This will include the original mail with all header info and send it to your recipient.