Howard,
It would, and does, to some degree - the trace header fields (particularly
Received) specify exactly this in RFC 5321 and RFC 5322. The problem is
that these can be faked by various means.
DKIM extends this to provide cryptographic proof of the chain of custody,
too.
So while one cannot find the originating IP address, one can find the last
known good server in the presented custody chain with some effort and
reasonable reliability. This doesn't stop spam in its tracks, of course,
but as you note it does help.
Dave.
On 22 April 2016 at 10:44, Howard Hong <howahong37(_at_)yahoo(_dot_)com> wrote:
Hello,
Would it help to stop spam by recording the IP address of the originating
server when open SMTP relays collect mail? Record the IP address in the
body of the e-mail, and record an IP address at each hop. Establish a chain
of custody so I can track an e-mail back to the source IP address.
Thanks,
Howard Hong