Message-ID

hello

i need to find a unique identifier for emails, so that if user A
forwards a message to B, and B to C, and so on... in user Z i can still
know that its the mail user A started.

when user A creates a message, it gets a Message-ID.
i found that most web based mail preserve this ID in some way (some put
it in "In-Reply-To" field, like gmail - when u FWD), others in
"References" header..
But outlook, for instance - totally kills it when i forward..

is there a way to do so? thanks.