Re: reject smtp connections if no valid reverse dns?

[acli@ada.dhs.org]

In article <20020722144253.C6428@redhat.com> you write:

>On Mon, Jul 22, 2002 at 09:34:43PM +0300, Matti Aarnio wrote:
>
>>   What I do to combat spam is reception content filter.  It rejects
>>   all messages smelling of HTML, and is amazingly effective way.
>>   Extending it to cover spam-assassin would be even more effective,
>>   but my time has been quite taken up lately...
>
>Filtering html was effective for quite a while, but they seem to have
>adapted.  Most of the spam that isn't being caught now is text only
>with reasonable headers (with valid, even forged From:).  Lately the
>regexps I use don't even catch the similar-but-different variations
>on the common scam mails.  Such a pain....

My thinking is that neither filtering against "correct reverse
DNS data" nor filtering HTML are valid ways to combat spam. A lot
of servers have wrong reverse DNS data (forward != reverse DNS,
especially if you consider some servers are .eu.org/.dhs.org hosts
with no possibility of getting correct or even existing reverse DNS).
And some HotMail users (and perhaps other) configure their accounts to
always send HTML.

(I am also using content-based filtering, and yes, I also notice that
my filters are failing a lot more recently.)


-- 
Ambrose Li  <a.c.li@ieee.org>   http://trends.ca/~acli/
                                              http://www.cccgt.org/
A good style should show no sign of effort;
  what is written should seem a happy accident. - Somerset Maugham
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