Simple feature request that will never happen: All Internet emails have a GUID field, and all users who have a copy of a unique message have that one GUID for it.
Why can't there by an "email:$MessageId" URI scheme and why can't Outlook handle these URIs with 1) open that message if I have it; or 2) "You did not receive that message."
I've looked into part of this before. Outlook has message URLs, specific to YOUR database, and they break if you move a message to another folder. Useless.
@progo
The issue then comes if you never recieved the original email, but had it forwarded to you...
You would want your clients to also check the References and In-Reply-To headers as a fallback.
@everlastingrocks yeah, forward as new text screws it all up. Good point.