Originally Posted by
cblaisd
I still don't understand why Outlook wouldn't reply to the address specified in the "Reply To" header?
Isn't that why that header/instruction exists?
Yes, but how many Outlook users would realize that the address that follows the [From:] label in the Outlook UI is
not actually the From: address (and should not be copied-and-pasted/added to the address book/etc.)?
Originally Posted by
cblaisd
Thanks for the clarification that this is a gmail-generated problem

It is not really a GMail-generated problem -- there are, in fact, a number of good reasons for including the Sender: header.
There are, however, no reasons for misrepresenting Sender: as From: