Look up message tracking, RFCs 3885-3888.
Arnt Gulbrandsen wrote:
I have a vague recollection that there once was an SMTP extension to
trace the path a message took after the fact. I cannot find it. Is my
memory playing tricks with me, or was there really such an extension?
(It doesn't matter whether the extension is odd, obscure and
unimplemented. I just need a fairly small part of it anyway. I want to
pass the ID assigned to the message by the sender-SMTP's to the
receiver-SMTP and log it there, and both sender and receiver are under