Mail delivery question

I have a somewhat dumb question about mail delivery.  This has a CP
connection because it relates to a remailer enhancement I am working
on.  When I receive mail from cypherpunks, this is a typical set of headers
for an incoming message:

  From owner-cypherpunks@toad.com  Wed Oct 20 23:57:11 1993
  Received: from nova.unix.portal.com by jobe.shell.portal.com (4.1/1.34)
  	id AA14713; Wed, 20 Oct 93 23:57:11 PDT
  Received: by nova.unix.portal.com (5.65b/4.1 1.505) 
  	id AA18779; Wed, 20 Oct 93 23:57:09 -0700
  Received: by toad.com id AA20355; Wed, 20 Oct 93 23:47:55 PDT
  Received: by toad.com id AA20115; Wed, 20 Oct 93 23:43:21 PDT
  Return-Path: <jamie@netcom.com>
  Received: from netcom.netcom.com ([192.100.81.100]) by toad.com id AA20111; Wed, 20 Oct 93 23:43:19 PDT
  Received: from netcom3.netcom.com by netcom.netcom.com (5.65/SMI-4.1/Netcom)
  	id AA27104; Wed, 20 Oct 93 23:43:51 -0700
  Date: Wed, 20 Oct 93 23:43:51 -0700
  Message-Id: <9310210643.AA27104@netcom.netcom.com>
  X-Mailer: Eudora
  To: cypherpunks@toad.com
  From: jamie@netcom.com (Jamie Dinkelacker)
  Subject: Re: Something Silly, Something Serious
  Status: RO

Now, my question is, when this mail is delivered to the Unix system which
I use, how does the local software know to deliver it to hfinney?  My name
does not seem to appear in the header at all.  In particular, the "To:"
address is not hfinney@shell.portal.com, as I would have expected, but rather
cypherpunks@toad.com.

I suppose there is some other information that is passed along with the
message when it is delivered to portal.com, information which tells my
user name.  It would be nice if this information were available to scripts
which would process the incoming mail.  Could someone explain how this
delivery process works?  Thanks -

Hal Finney
hfinney@shell.portal.com

Hal Finney says:
> Now, my question is, when this mail is delivered to the Unix system which
> I use, how does the local software know to deliver it to hfinney?  My name
> does not seem to appear in the header at all.  In particular, the "To:"
> address is not hfinney@shell.portal.com, as I would have expected, but rather
> cypherpunks@toad.com.

All mail has two sets of "To" addresses. There is the ENVELOPE
address, which you do not see, and the HEADER address, which is mere
window dressing. I could have the headers say "To: That Lousy Schmuck"
and the mail would still arrive. The envelope and header addresses
have to be kept seperated for all sorts of very sound reasons that I
could explain happily in private mail. The envelope address is passed
around using the "RCPT" command in SMTP and is never contained in the
mail message itself.

Perry

I was pondering the same question awhile ago.  After poking around in
the system and reading the temporary scratch files that the system
created by the mailer, I noticed that the mail was being preceeded by a
seperate header packet which was not included in the message.  Sending
mail to myself caused the system to create two temporary files in the
process.  One of them was called "SF" and the other was "QF".  I don't
know what the letters stand for, and this is probably just how CMU does
it, other sites may be different.  Anyway, in my test mail to myself,
the SF file contained:

#From |<mg5n+@andrew.cmu.edu>|
#To |mg5n+@andrew.cmu.edu|
#Auth |26634;andrew.cmu.edu;Matthew J Ghio|

and the QF file contained the actual text of the message plus the
headers that you see.  So the email is actually sent as two seperate
packets of data, the headers you see are just there for looks, the
actual delivery info is hidden behind-the-scenes.  Does anyone else have
any description of "standard" methods of handling internet e-mail?