Lewis, Chris (CAR:W669) wrote:
Ian Eiloart wrote:
--On 2 July 2009 12:27:57 -0400 Chris Lewis <clewis(_at_)nortel(_dot_)com>
Bill Cole wrote:
Ian Eiloart wrote, On 7/2/09 6:23 AM:
Exercise for the reader: why aren't spammers using the @ibm.com domain?
You provided the answer before the question.
Somewhat. Because spammers _are_ using @ibm.com too. I got samples ;-)
Ok, but it's trivial to reject them after checking SPF.
Don't need to. They're all being rejected by either "no such user" or
the spam filter rejects.
SPF isn't worth the cycles nor bandwidth (in this environment at least)
to catch the rare SPF -all.
I should add - _if_ spammers are using the "-all" to screen out bad
senders to use, then the mere existance of SPF as a "standard" has some
value to push spammers away from forging certain high-value-target
domains literally and thus marginally reduce backscatter because of
But it doesn't imply that implementing any SPF checking will make any
noticeable difference. Indeed, the only concrete numbers I've ever seen
about SPF adoption were percentages of domains publishing SPF records
due to noises being made by MSN/Hotmail, _not_ checking SPF.
Nobody has a handle on how many have actually implemented SPF checking.
The only stats I've seen about backscatter volume pre/post SPF
publication don't show any compelling reason to believe SPF made any
difference. There's no particular reason to believe that it's going to
get any better either.
We publish, but do not check simply because of the noises that
MSN/Hotmail were making. Publishing (and erroneous checking) has
probably caused more problems (elsewhere) than it's solved.
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