Re: [Exim] Greylisting + multiple MX hosts -> multiple attem…

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Szerző: Ian A B Eiloart
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Címzett: Exim users list
Tárgy: Re: [Exim] Greylisting + multiple MX hosts -> multiple attempts
>
> Do you have any references for that?


Well, you've probably seen what I
have:<http://news.bbc.co.uk/1/hi/technology/3458457.stm>

> The only reports I've read have been for a very specific set of words.
> The researcher used their own filter and repeatedly refined the search
> based on the results of that filter. I've not seen anything involving a
> set of words which could be got through a generic Bayesian filter - after
> all, everyone's mail is different and the number of words and occurrence
> of each in the spam/ham list will be different.


True, but that's not necessarily a problem. For example, someone
advertising a family oriented product won't mind if only family people read
their emails. In fact, spammers could even benefit by getting better click
through rates if bayesian filters are doing a good job of throwing away
mail relating to topics I'm not interested in.

Targeting our server, or any .edu or .ac.uk domain, throwing in a few key
words like "funding", "research", "sussex", "marks", "educational" and so
on, is likely to reduce your spam score.

They can even gather feedback - if mail clients display html, and fetch
remote images, then spammers can collect data on how well they're doing.

Anyway, I'm not saying that Bayesian filters shouldn't be used, or that
they won't reduce the amount of spam you get - they probably always will. I
was simply responding to someone who argued that greylisting was a
one-trick pony that would fail in time.

My view is that we need all the tools we can get, including greylisting,
Bayesian filters, and so on.

> The only time I could see this approach working at all is for a system
> which used a standard Bayesian database. No good spam filter would do

that, and with subsequent training the statistics/database would alter
anyway.
>
> --
> Nigel Wade, System Administrator, Space Plasma Physics Group,
>              University of Leicester, Leicester, LE1 7RH, UK
> E-mail :    nmw@???
> Phone :     +44 (0)116 2523548, Fax : +44 (0)116 2523555

>
>
> --


--
Ian Eiloart
Servers Team
Sussex University ITS