Re: [OT] Tom's/Marc's spam filters?

Bruce Momjian <pgman@candle.pha.pa.us> wrote:
>
> Jim Seymour wrote:
> > Bruce Momjian <pgman@candle.pha.pa.us> wrote:
> > >
> > [snip]
> > >
> > > I don't have any problem using a backup MX.  My sendmail rules skip over
> > > the received line from my MX and check the host that sent to my MX.
> >
> > What do you do if you don't like the client that delivered it to your
> > backup MX?  You can't just throw it away.  Well, you *can*, but doing
> > so breaks the email delivery system.  If reject it, your backup MX will
> > then bounce it to the ostensible sender, which is very likely forged.
>
> For stuff I block via sendmail, I 550 it, even from my MX.  I am not
> sure what my MX does with it, but no one has complained.
[snip]

What it should do, and probably does do, with it is bounce it to what
it believes the sender to be.  Problem with that, as I noted earlier,
is that the sender address in spam is frequently forged.  Sometimes
forged to be a valid, tho innocent, person.

Trust me: You really shouldn't do that as standard policy.  See the URL
I mentioned earlier, in reply to Tom (IIRC), pointing to a bit I wrote
on backup MX servers.

Mail admins are beginning to find such mis-bounces nearly as
objectionable as the direct spam.  There's been some discussion that
spammers may even be using known "mis-bouncing" servers as
"reflectors," to propagate spam.

--
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