Can I have set a different "Reply to" email address for an outgoing
email, so that when somebody hits reply, the response will go to that
different email address?
Create a reply to header.
Go to Tools -> Accounts.
Under the Mail tab, edit the mail account you want to send from.
Click the Options tab.
Under "Additional Headers", add in a new header: Reply-to
Under Value, enter the e-mail address you want recipients to reply to.
Note that this will only be the suggested return address - senders can
still choose to contact you from your sending address - for example in
Entourage, the Reply command will reply to the default reply address,
but the Reply to Sender command will reply to the sending address
regardless of whether a Reply-to header is present.