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Date:      Thu, 19 Mar 1998 17:46:11 -0500
From:      Joe Mays <jfmays@launchpad.win.net>
To:        freebsd-isp@FreeBSD.ORG
Subject:   Re: spam blocking in sendmail
Message-ID:  <3511A033.6A780275@launchpad.win.net>
References:  <199803191812.KAA07542@hub.freebsd.org>

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On a related note: I just ran into an issue today with
spammers that leads me to a sendmail.cf question.

Someone out there is generating spam mail (we've encountered
it from more than one domain) that has a blank X-UIDL:
header.  This is a real problem for MS Outlook and Outlook
express.  When they attempt to download messages from the
pop server which contain this header they hang and give a
pop-server timeout.  Netscape has no problem downloading
them, though it may screw up the indexing in the inbox list,
not sure about that yet.

In the strictest sense this is an MS Outlook problem.  The
blank X-UIDL header should not halt the download.  In the
real world, it looks to our customers as though our pop
server is dying.  Does anyone know if it is possible to have
a sendmail.cf ruleset that watches for empty X-UIDL headers
and bounces them if they occur.

Re: Outlook, if the header is present and has a value,
that's fine.  If it's not there at all, that's fine too.  If
it's there but has no value, hang-time.  I'm not sure why a
spammer would want to generate a message with the header
like this.

Jonathan M. Bresler wrote:
> 
> Steve Hovey wrote:
> >
> > Ive found what looks like a good way to block inbound spam by domain - but
> > am not up on sendmail enough - it mentions making a hash table
> >
> >
> > FK/etc/mailspamdomains
> >
> >
> > Is that just text you leave be? Or do you have to issue some kind of
> > makemap on it?  It doesnt mention doing anything - but I thought I would
> > check.
> 
>         wow....that all depends upon what is in your sendmail.cf
>         FK/etc/mailspamdomains declares a database file called
>         /etc/mailspamdomains.   nothing more.
> 
>         take a look at /etc/mail/sendmail.cf.additions
>         and /etc/mail/README.
> 
>         we use those anti-spam rules.
> jmb
> 
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