On Thu, 23 Jun 2005, Roger B.A. Klorese wrote:
Then you don't have a forwarder. If it's a forwarder, it doesn't
re-address. If it re-addresses, it's not a forwarder.
I think we have a terminology problem.
This conversation hinges on the distinction between relaying - passing
a message on to another MTA unchanged except maybe to
add a Received header, and "resending" - sending on a message
with this MTAs domain in the MAIL FROM, and possibly changing
or adding multiple headers.
Some of us, like Roger are using "forward" to mean "relay".
Others of us are using "forward" to mean "resend".
So let's get rid of the word "forward", since it is ambiguous
in this company. I'll restate my claims using "resend" and "relay",
and you can do the same for others arguments.
Stuart claims:
1. SPF does not break resending a message.
2. SPF does not break relaying, because SPF does not apply and
should not be checked for relays. Relaying should only be done
between MTAs with an administrative relationship. (For example a
secondary MX to a primary MX.)
I believe Roger is claiming that every ISP should accept relayed mail
from any MTA. Notice that without an administrative relationship,
the ISP has no way to know which messages are relays, and therefore
not subject to SPF. Hence, under Rogers rules, the ISP cannot apply SPF
at all without breaking the relays.
I disagree with Rogers approach because it is half of an open relay. A fully
open relay allows any sender to relay mail to any recipient. This was also
once common practice on the internet, and people complained bitterly
when open relays were eventually isolated and ignored.
The half-open relay advocated by Roger restricts recipients to
the set of addresses configured by users, but still
allows relaying by any sender. This is a problem, and
while still common practice, such half-open relays will likewise
be gradually isolated and ignored for the same reasons.
--
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.