I don't use razor, spamassasion or spamcop. I just don't
trust leaving the rules to something outside my control.
My current technique is a header scoring system I wrote
myself and it works pretty well. But it requires tweaking
from time to time, so I've been looking around at other
methods.
Statistical analysis of content is starting to look quite
good. Here are some links:
A Plan for Spam (outlines the rational and evidence of
success for this):
http://www.paulgraham.com/paulgraham/spam.htmlbogofilter (Eric Raymond's implementation of this)
http://www.tuxedo.org/~esr/bogofilter/ifile (similar vein, but generalized to multiple categories)
http://www.ai.mit.edu/~jrennie/ifile/I started tagging my email with ifile results today after
seeding it with my spam-box and non-spam mailboxes, and
it has properly tagged the 4 pieces of spam and 15 pieces
of non-spam I've gotten this afternoon.