Re: [off-topic] spam-filters

["Randy Brukardt" <randy@rrsoftware.com>]

Wes Groleau wrote in message
<1ciS9.217$Z74.1099@dfw-service2.ext.raytheon.com>...
>
>> joking. My ISP caught 37 for January 3). But I almost never have to
look
>> at a spam any more. I think in the last week Mozilla let about 2 slip
>> through, and hit one false positive.
>
>Can it catch them just by headers, or does it evaluate
>for spam AFTER it downloads the entire piece of crap,
>complete with HTML bloat (generated by Microsoft Word
>or some equally lame thing that toggles styles on and
>off multiple times on every line) and all the stupid
>graphic attachments?


Actually, most spam these days are short HTML messages with little or no
text. There isn't much load on the server from them. Simply blocking
HTML graphics gets rid of many of them. Also, a lot of spam is now
encoded in various ways so that simple text filters can't find them.

The big messages tend to be real or are viruses. (I'm seeing 3-5 viruses
a day in the various filters; most are sent to the public webmaster and
mailing list addresses we support.)

I know this well, because I wrote a spam-filtering plug-in for our
mailserver (in Ada, of course). Our mail server is receiving about 150
messages per day, of which the filter passes only about 15%. About 30%
are so frequent and obvious that I'm able to match them and autodelete
them. And many of those get caught by the (old) blacklist filtering,
which runs after my filter.

                  Randy Brukardt