|
[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]
|
Re: [PLUG] spam abatement with a challenge/response system
|
On Sun, Oct 22, 2006 at 08:43:24PM -0400, Eric wrote:
> While exploring the internet for something else entirely I found mapSoN -
> a challenge/response system for filtering email.
Disclaimer: I work for Symantec Mail Security. I don't speak for Symantec.
Using a C/R system, you will end up dealing with email for a period of
time just the same. Instead of dealing with spam, you will find yourself
dealing with the consequences of breaking email as others know it.
Personally, I would never respond to your C/R system on principle, as it's
an ostrich-style solution that doesn't scale. Eventually, your "whitelist"
will become corrupted and you will have to hunt through to remove the
erroneous or overzealous listings.
As well, you may not even be notified that someone was attempting to email
you (the point of C/R systems, indeed), so you may potentially miss a
time-sensitive email from an unknown entity. By using a C/R system, you
are making the implicit statement that your time is worth more than those
wishing to correspond with you, something that you can probably understand
will rightly aggravate some of the aforementioned group (myself included).
Finally, they are not foolproof. If I can guess an address on your
whitelist, I can spam you all day long. This is a lot easier than you
think. At the 2004 MIT Spam Conference, I literally did this very thing to
a guy presenting his C/R system while he was giving the presentation and
then used it to send him a message that bypassed his C/R shield. More to
the point, joe-jobs that forge the From: address will still hit you if
they forge an email address on your whitelist. A C/R system coupled with
something akin to DKIM would be truly (or at least a lot more) effective,
but no such system exists today.
It is an unrealistic goal in this day and age to want to a) have an email
address, but also b) spend no time on dealing with spam. Spam comes with
email these days. Open a Hotmail account right now and you will receive
your first spam to that account in under 10 minutes, regardless of whether
or not you gave anyone the address.
A more effective and less problematic approach to spam filtering for you
personally would be a naive Bayes classifier, e.g. bogofilter [1] or
DSPAM [2]. Also, I was using Apple Mail's embedded LSI classifier to good
effect before I stopped using that MUA, but this is only available if you
are running OS X.
P.S. SpamAssassin, straight out of the box with no customizations, is not
very effective. However, with some tuning it can achieve 95% catch rate or
higher, I'm told. It remains a resource hog regardless of the tuning you
do.
[1] http://bogofilter.sourceforge.net/
[2] http://dspam.nuclearelephant.com/
--
Toby DiPasquale
___________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
|
|