the linux documentation project spam statz:

   44391   62.67%  DENIED_RDNS_MISSING
   16099   22.73%  DENIED_RDNS_RESOLVE
    3254    4.59%  ALLOWED
    2439    3.44%  DENIED_RBL_MATCH
--------------- Breakdown ---------------
    5226   80.59%  zen.spamhaus.org
    1258   19.40%  bl.spamcop.net
-----------------------------------------
    1879    2.65%  DENIED_SENDER_NO_MX
    1133    1.59%  DENIED_IP_IN_CC_RDNS
    1099    1.55%  ERROR
     438    0.61%  DENIED_TOO_MANY_RECIPIENTS
      72    0.10%  TIMEOUT
      17    0.02%  DENIED_RELAYING
       2    0.00%  DENIED_OTHER

---------------- Summary ----------------
Allowed:     3254    4.59%
Timeout:       72    0.10%
Errors :     1099    1.55%
Denied :    66398   93.75%
Total  :    70823  100.00%