On Mon, 21 Feb 2005, David MacQuigg wrote:
1) Each forwarder must independently authenticate its immediately
connected sender, relying on the IP address in the SMTP session with that
sender.
I.e., SPF.
2) The results of the authentication must be pre-pended to the headers of
the incoming mail, making it available for all subsequent receivers.
This is already defined as the Received-SPF header.
4) The syntax of the authentication header should be simple and well
defined, even if that means introducing a whole new header that repeats
information in existing headers. There may be a problem with all the
currently allowed variations in Received: headers.
The Received-SPF header is well defined as far as how the final result
is communicated.
5) Bounces and rejects must go back the path they came, not to some header
address that might be forged.
Unless the IP gets an SPF PASS, the only way to do that is to issue an SMTP
REJECT.
6) The protocol must allow for an arbitrary number of forwarders between
the sender and the receiver.
No problem.
Here is my proposed new header to meet these requirements:
Authenticate: SPF1 [<IP Address>] <senders-domain> PASS
What is wrong with the header already defined? Here is the last two PASSes
from my log for example:
Received-SPF: pass (mail.bmsi.com: guessing: domain of fifthwater.com
designates 193.28.182.113 as permitted sender)
client-ip=193.28.182.113;
envelope-from=Francina_Mickel(_at_)fifthwater(_dot_)com;
helo=fifthwater.com;
Received-SPF: pass (mail.bmsi.com: domain of mx6.rambler.ru
designates 81.19.66.150 as permitted sender)
client-ip=81.19.66.150;
envelope-from=postmaster(_at_)mx6(_dot_)rambler(_dot_)ru;
helo=mx6.rambler.ru;
and here is a NEUTRAL:
Received-SPF: neutral (mail.bmsi.com: guessing: 202.47.165.130 is neither
permitted nor denied by domain of MTS_PDC.drbhicom.com.my)
This header is defined as part of the SPF drafts.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.