Sat, 11 Nov 2006
Postgrey statistics
I wrote about an increase of spam volume in the previous month, and also about installing Postfix to the IS MU mailserver. Here are results after 10 days:
The total volume of my spam last month was lower than expected - only 1.3GB in 94k messages, so the increase was 1.6 times in size and 1.3 times in number of messages. However, the total number of spam going to other mailboxes in our domain has increased by 50% or more.
I also wrote that have installed Postgrey to the IS MU mailserver, hoping that greylisting[?] would deflect a majority of spam from IS MU. However, I did not found a decent statistics package for Postgrey, so I hacked up a simple script to generate statistics from Postgrey. It is too simple and possibly not entirely correct, because Postgrey does not provide much info in its log. Here are the stats from the first 10 days:
Greylisting stats from Nov 1 00:00:00
till Nov 10 15:38:03
Messages
total: 2072453
accepted immediately: 179692 ( 8.7%)
delayed: 22473 ( 1.1%)
blocked: 1870288 ( 90.2%)
Greylisting delay (avg): 4399s delayed
550s all
SMTP servers:
hosts messages
No message accepted: 231940 1840367
No message graylisted: 1364 163021
All accepted (maybe delayed): 7750 21281 = 33243-11962
More blocked than accepted: 2112 34531 = 40432-5901
So it seems that 90% messages are spam which can be blocked by greylisting. Nice. The next problem is to recognize spam in the remaining 10%.