Thus said Ralph Corderoy on Sun, 22 Feb 2015 13:53:41 +0000:
Stop sending outgoing mail through comcast as the smarthost; Gmail is
the smarthost instead. You won't persuade the rest of the world that
you're really dnc2dnc@gmail.com unless your email eminates from
Gmail's servers. As well as publishing DNS TXT records containing SPF,
Google also use DKIM.
If by ``rest of the world'' you mean Hotmail, Gmail and Yahoo, you may
be right, but what percentage of the other ``rest of the world''
actually rejects SPF and DK when their SMTP receives email? Not even
Hotmail does that; I can sucessfully send an email using a MAIL FROM
with a forged hotmail.com/gmail.com address and they will gladly accept
it, despite the fact that my IP address is not in their TXT record.
This means they are just using SPF (I guess their TXT record does have
~all) as a piece of evidence that is used to inform their email filters,
but if SPF and DK were really that useful to ``the rest of the world'' I
suspect they would outright REJECT the email rather than accept it. That
they don't leads me to believe that allowing arbitrary addresses in MAIL
FROM is still a useful thing, even for them.
All this tells me that they don't have very intelligent filtering tools,
and that SPF and DK are just getting in the way of better approaches. A
simple naive bayesian filter (per user) would probably do better.
In addition, I took the liberty of sending an email to @hotmail.com
using your domain of @inputplus.co.uk which has a published SPF
specification:
$ dnstxt inputplus.co.uk
v=spf1 a:ruis.pair.com include:relay.pair.com include:webmail.pair.com -all
Hotmail accepted the message, despite the fact that your domain includes
-all. Guess SPF isn't that useful for inputplus.co.uk after all...
How does this help Bob? Not much, except to say that even with all the
ducks in a row, any changes he implements may still not help. Filters at
Gmail/Hotmail/Yahoo may or may not still decide to throw the message in
the Spam folder. Then what?
Andy
--
TAI64 timestamp: 4000000054ea1da9
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