Low spam detection

[Denis Beauchemin]

Hello all,

I am seeing a significant decrease in spam detection over the last 
months and I was wondering if anyone else was seeing the same trend on 
their servers.

Here are my stats from the start of 2008:
month       emails        spam       virus      spam%    virus%
2008-01    7 337 089    6 348 633     59 386    86,5%    0,8%
2008-02    6 203 500    5 152 249    123 029    83,1%    2,0%
2008-03    8 118 670    7 010 463    140 891    86,3%    1,7%
2008-04    7 693 698    6 569 030     98 957    85,4%    1,3%
2008-05    7 956 170    6 927 306     81 625    87,1%    1,0%
2008-06    6 342 232    5 380 464     86 449    84,8%    1,4%
2008-07    6 779 005    5 866 915    102 319    86,5%    1,5%
2008-08    7 592 171    6 687 128    123 659    88,1%    1,6%
2008-09    8 947 295    7 779 344    125 637    86,9%    1,4%
2008-10    7 092 938    5 873 751     66 896    82,8%    0,9%
2008-11    5 093 559    3 917 609     73 225    76,9%    1,4%
2008-12    4 602 584    3 519 119     44 382    76,5%    1,0%
2009-01    3 568 832    2 430 698     36 931    68,1%    1,0%
2009-02    3 253 018    2 089 179     52 037    64,2%    1,6%
2009-03    3 341 614    2 050 365     66 486    61,4%    2,0%

My servers are quite current: RHEL 5.3, SA 3.2.5-1 with many SARE rules 
and KAM, DCC, Pyzor and Razor, Clam 0.95 with Sanesecurity and some 
others, and many RBLs in sendmail.

Every email blocked by a RBL is counted as spam (because it probably 
is). Emails detected by Sanesecurity et al are counted as viruses.

Do you have any ideas what could account for such abysmal spam rate 
detection? I can see the total number of emails received dropping 
significantly in the last 6 months.  Have others seen the same?

Would DefenderMX help stop more spam?

Thanks everybody!

Denis

-- 
   _
  °v°   Denis Beauchemin, analyste
 /(_)\  Université de Sherbrooke, S.T.I.
  ^ ^   T: 819.821.8000x62252 F: 819.821.8045