On Thursday, April 17, 2014 6:53 PM, John Levine wrote:

>> I don't see any scaling problem for the case of a domain used by a single
>> entity that wants to authorize a few service providers to send email on
>> its behalf.
> Is that really a problem? I was under the impression that a sender either
> adds the providers' IPs to their SPF record, or gives them a DKIM signing key.

wrong:
1. DKIM key sharing requires such a support, which is usually not there.
2. SPF policy check doesn't evaluate ur SPF policy at all, but ur ESP's.


On Thursday, April 17, 2014 6:53 PM, John Sweet wrote:

>> I am still curious what's wrong with this proposal.
> How is this not covered by SPF "include:"? If your message has both MAILFROM
> and RFC822 From: aligned on your domain, and the connecting IP is in the
> range of the included domain, it's all good.

it isn't covered by SPF's "include:".

seems not many understand this problem, let me make an example:
if i use yahoo email for my goodone.tk domain, yahoo will send my email
with yahoo.com DKIM key and with yahoo.com SPF MailFrom [my yahoo account
address].

and i can't do anything about it. yahoo doesn't support key-sharing, nor
it will.

so, my domain-email sent from yahoo mail isn't aligned. however, it is
legitimate, it is DKIM-signed and it has proper SPF.

out of my 15 small-business customers, 12 use exactly this usage scenario.
usually google. and when i said it would be a problem, that was not the best
way, trying to force them to send mail through their own server, they didn't
want to hear it.

and i imagine, it is a pretty common practice in the wild for small players.


-- 
Vlatko Salaj aka goodone
http://goodone.tk

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