On Oct 15 2007, Dave Crocker wrote:
The field does not define a sender. It defines a receiver.
That is not a very useful way of thinking about it. The return path
identifies (something to do with) the sender as much as the Sender: and
From: fields do. The originator fields all define receivers of messages,
but only those sent in response to the current message, which is a bit
irrelevant. It's best to talk about exactly one message at a time when
defining which addresses identify receivers to avoid confusion.
What is special about the return path is that it's the only address to
which bounces may be sent, and it isn't used for other kinds of response.
Hence the usefulness of VERP techniques.
f.a.n.finch <dot(_at_)dotat(_dot_)at> http://dotat.at/