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Re: Reduce the amount of spam for @debian.org (Was: Greylisting for @debian.org email, please)

gmail.com used to do that to lists.debian.org. We deliver ~300,000
emails to gmail a day. It resulted in some deliveries timing out before
they were even attempted; I'll let you imagine the rest.



On Fri, 2005-06-17 at 08:35 +0200, Petter Reinholdtsen wrote:
> [Santiago Vila]
> > For example, we could use greylisting. Or we could reject messages that
> > are known to come directly from trojanized windows machines acting as
> > open proxies. Or even better, we could do both things.
> Or a completely different option. Here at the university the
> postmasters implemented a system to delay delivery based on blacklist
> entries.  The delaying is done during the first connect, and does not
> require the MTA in the other end to reconnect, like greylisting.  The
> idea is simple:
>  - Keep/use a list of good and not soo good blacklists for MTA hosts.
>  - If the other side is listed in one of this blacklists, act as a
>    _very_ slow SMTP server.  The initial hello reply is delayed 1-2
>    minutes in this case, and if the client try to send anything in
>    this period, the connection is dropped.  The SMTP protocol specifies
>    that the client should not send anything before receiving the intro
>    line from the other end, so this is safe to do.
>  - This reduced the amount of spam with more than 90 percent, I've
>    been told.  The current spam software do not seem to have time to
>    wait for a reply, or give up the delivery after a few seconds
>    without any reply.  In either case, all standard-compliant MTAs are
>    able to get their mails through, even if they are listed in a
>    blacklist.
>  - MTAs not listed in a blacklist is passed throught without any
>    delays.
> Could this be an idea for Debian as well?

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