On Fri, 8 Jul 2005, wayne wrote:
In
<1120833949(_dot_)27264(_dot_)11(_dot_)camel(_at_)hades(_dot_)cambridge(_dot_)redhat(_dot_)com>
David Woodhouse <dwmw2(_at_)infradead(_dot_)org> writes:
But SPF doesn't work without SRS.
David: It is statements like that where you lose all credibility.
SPF does work, without SRS.
Wayne, you are correct. But I found I could understand David's
arguments much better when looking at it from his point of view.
He is apparently a forwarder. He can't depend on his users
being smart enough to list his service as a trusted forwarder
if needed (i.e. if the users ISP reject on FAIL). So from his point of view,
SPF does not work without SRS.
Technically, yes, SPF is not broken, but is being used incorrectly. Either
the user's ISP shouldn't be rejecting on FAIL, or the user forgot to list
his/her forwarder. But the customer is *never* wrong. Therefore, from
David's point of view, it is SPF that is broken. Once you understand
that, all his arguments make sense. Maybe not technically,
but they make sense.
Really, the only choice David has to ensure that his service operates
smoothly with recipients that may or may not correctly implement
SPF checking (no matter how screwy their received mail policy,
the customer is *never* wrong), is to use some form of SRS. And
since customers and their ISPs will have different screwy localpart rules
(like banning '+', say), he will have to be able to customize how and whether
he does SRS for each forwarding target. This is a lot of effort and
expense on David's part, and he will have difficulty raising his
rates to cover it. I do not envy his position, and I can understand
his frustration.
Most of us haven't encountered any forwarding problems with SPF.
That is a good indication that they are rare overall. However,
*all* of David's SPF problems are forwarding problems due to the
nature of his business. This gives him a very different perspective.
--
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.