On 9 May 1998, Wolfgang Rupprecht wrote:

: Actually, much of the spam that homeworld.cygnus.com forwards could be
: stopped with the current sendmail 8.9.0 run as a front-end filter for
: qmail doing the final delivery.  (Phony "from" filtering and
: spam-software-only header filtering does a surprisingly thorough job.)

Phony "From:" filtering is also a way to completely block an average site
from using a news<->mail gateway, as most people post to USENET with fake
e-mail addresses specifically to stop spam because of their posts.  If
you're filtering mail based on the "From:" field and using any of my mailing
lists/gateways (and I have hundreds of them), chances are you won't be using
them for long. 

Now, phony _envelope_ filtering is something else, and something I use on my
own site (it's specified as a recommendation in a RFC).  I also use the
Realtime Blackhole List (http://maps.vix.com/rbl/) on all mail servers I
host.  But I refuse to put "From:" filtering on them because of reasons
stated above. 

-- 
-- Todd Vierling (Personal tv@pobox.com; Bus. todd_vierling@xn.xerox.com)