I was looking at the logwatch output from RubyForge the other day and noticed this in the Postfix log section:

   34652   Accepted                                   5.30%
  618877   Rejected                                  94.70%
--------   ------------------------------------------------
  653529   Total                                    100.00%

Almost 95% of all SMTP connections are spam! My goodness. Here are the detailed stats:

    1824   Reject relay denied                        0.29%
   24225   Reject HELO/EHLO                           3.91%
  264808   Reject unknown user                       42.79%
  149903   Reject recipient address                  24.22%
  178112   Reject sender address                     28.78%
       2   Reject server configuration error          0.00%
       3   Reject VRFY                                0.00%

Mostly unknown users - spammers doing dictionary attacks, I reckon.

Speaking of spam, we use the Postgrey greylisting daemon to, well, do greylisting. A few weeks ago I noticed that it was constantly blocked on I/O and was taking up a good bit of CPU as well - I guess that's to be expected when you've got a 70 MB postgrey data file. Anyhow, I moved the daemon over to another box, twiddled the Postfix configuration on one end and the iptables configuration on the other end and the Rubyforge load average dropped a good bit. Good times.