Abrupt spam increase

[richb at pioneer.ci.net (Rich Braun)]

I've noticed over the past 6 weeks a sudden, abrupt increase in the flow of
spam on my home server.  It's gone from about 250/day to 440/day; last month's
average daily flow was about 360.

Thus far I've been simply directing it to a quarantine folder, and keeping
general tabs on the volume.

But as volume grows, at some point I'll want to do something different.  I
have a couple of questions:

(1) Have any of y'all tried to keep stats on the flow of spam?  Are my
observations about message flow on-target?
(2) Beyond SpamAssassin, have you tried out any tools which reject spam before
it reaches your mailbox?  I know that I could configure sendmail to reject
mail from sites listed in certain blacklist databases, but before I take that
step I want to make sure to use the right blacklists and I also want to keep
better statistics on a per-recipient basis (example, I get mail to "daemon"
and "amanda", in addition to "richb", at my domain).
(3) Are there any spam-folder statistical analysis tools that are useful?

I'm not sure why I care to keep stats, but somehow I think it'll be useful in
the future.  Having piles of old spam on-tap has often helped me to craft new
rules to block the deluge.  Local rules that I've defined here keep 99% of
spam out of my in-box and another 80% of the remaining flow gets tagged on the
subject line.

-rich