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Re: Stop spammers sending us spam from users in our domain...

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  • mouss
    ... Most sites should no more care about this issue , in these days of SASL and/or SPF...
    Message 1 of 14 , Aug 1, 2009
      Matthew D. Fuller a écrit :
      > On Wed, Jul 29, 2009 at 03:03:43PM +0100 I heard the voice of
      > Clunk Werclick, and lo! it spake thus:
      >> My apologies for the terse caveat. As I understand it, there are
      >> some external mail services that roaming users may use that forward
      >> mail into your Postfix claiming to be from your domain. Myself I do
      >> not use this.
      >
      > The problem doesn't come from what you use, but from what any of your
      > users may somewhere use.
      >
      > Imagine you are example.com, and have two users, a@..., and
      > b@.... a@... sends mail to b@... (which
      > you don't control, and know nothing about, short of looking up its MX
      > record and sending the mail on its way). But b@... is
      > just a forwarder and forwards the mail on to b@.... That
      > forwarder won't (and quite probably _shouldn't_) change the envelope
      > sender. Suddenly, you have mail from "outside", with an envelope
      > sender that's you, but is perfectly legitimate. And pretty common.
      >
      > If you know all your users and know none of them do any such thing,
      > filtering it works great. But if you're not absolutely sure, you
      > could be setting out landmines.
      >
      >

      Most sites should no more care about this "issue", in these days of SASL
      and/or SPF...
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