On Sat, 17 Apr 2004, Seth Goodman wrote:
I put forward the proposition that SES does everything that SPF+SRS does,
delivers more confidence in the end result and causes less breakage. Here
are some arguments to support this position.
3) SES allows the final recipient to directly query the domain MX for
verification and have high confidence in the result.
Note that callout verification works across firewalls etc., if it is
routed in the same way that a normal message would. E.g. an MUA would do a
callout via its smart host, which would in turn callout to the MX in
order to check the envelope presented by the MUA.
7) SES does not break forwarding, which makes it very easy to phase in.
SES does not break forwarding on the outgoing path of a message, but it
does place restrictions on forwarding bounces -- a signed envelope sender
address must refer directly to a mailbox on a final delivery system. (If
the bounce is forwarded it will end up with unsigned recipient address
which is not valid for bounces.)
11) SES is easily extended to verifying addresses in the 822 header. If
a standard SES address format is used such that an MUA can turn an SES
address into an unsigned recipient address, you can do something like
From: Tony Finch <dot(_at_)dotat(_dot_)at>
Verify-From:
<SES0(_dot_)SVoTm6oIlgKDmBlRbOmA(_dot_)dot(_at_)dotat(_dot_)at>
The MUA knows the addresses correspond, and can verify the SES form using
a callout. This is trivially extensible to multiple From: addresses,
Sender: addresses, and Resent- addresses, etc.
--
Tony Finch <dot(_at_)dotat(_dot_)at> http://dotat.at/