RBL check combines SMTP sender and Mail_From domains

Gary Mills mills@cc.umanitoba.ca
Fri Sep 19 13:29:36 UTC 2008

On Mon, Sep 15, 2008 at 02:05:54AM +0000, Vernon Schryver wrote:
> > From: Gary Mills <mills@cc.umanitoba.ca>
> > > As I always say, wanted bulk mail should be whitelisted.  One of the many
> > Of course.  The difficult part is determining which messages should be
> > whitelisted.  People generally don't notice that e-mail is being
> > rejected until it stops arriving.  We use a shared whitelist here to
> > which people can nominate messages after they have been rejected.  The
> > advantage is that only one recipient of a legitimate bulk mail message
> > need nominate it.

> I think the best tactic is to give each user a private dccm/dccifd
> whiteclnt file and log directory.  Users can check their private
> logs and white- or blacklist as they wish, and even set thresholds,
> turn DCC checks and greylisting on or off, and so forth with something
> like the proof-of-concept CGI scripts demonstrated at
> https://www.rhyolite.com/DCC-demo-cgi-bin/edit-whiteclnt
> with username cgi-demo and password cgi-demo

My impression is that most users don't want to bother with identifying
and classifying spam; they just want their e-mail to work.  They'd be
happiest if the spam filter could make all those decisions on their
behalf.  Of course, that's impossible because only recipients can know
if they've requested a particular message.  The other end point is to
have users make all of the decisions.  That would be a nightmare here,
as the majority of users wouldn't bother to check a web page.  Some
users are also not very good at recognizing spam or phishing e-mail.
Our compromise is a shared whitelist, to which any recipient can
contribute.  This certainly isn't a perfect solution, but it is

> I recall being told that is not practical at U of M, but it is done
> as some other sites.

I suspect that the most common technique now is to combine DCC with a
number of other tests, and then to deliver messages identified as spam
to a spam folder.  I do prefer the SMTP-level rejection that DCC does.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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