On Tue, 04 Nov 2014 08:05:22 -0700, BC wrote:
> At the suggestion of others here, I turned OFF greylisting last year, 
> after having used it for years before that.  My spam level didn't 
> increase one bit.  I think the RBL sites are pretty good at 
> identifying spam originations, so I use that method now.

So to check the usefulness of greylisting, I've done a rough study on our 
server. I've run three ten-day periods with different configurations, and 
processed the logs for each period using David Ramsden's SpamAssassin logfile 
analyser script [1]. 

The difference between greylisting enabled or disabled, all other configuration 
the same, is 2x the amount of messages received. During the period of 
greylisting, no false positives were reported by our users although they said 
their spam load was significantly reduced. It's hard to know from these number 
what the actual change in spam is, but I would venture to interpret the results 
and say greylisting is still helpful. You can see my spamdyke configuration 
here [2].

Config 1: SA + rblsmtpd

Total messages:                Ham:       Spam:      % Spam:   
90824                          56264      34560      38.05%

Average spam score            : 11.34/4.78
Average ham score             : -0.01/4.85

Config 2: SA + spamdyke (no greylisting)

Total messages:                Ham:       Spam:      % Spam:   
78271                          63730      14541      18.58%

Average spam score            : 10.00/4.80
Average ham score             : -0.05/4.85

Config 3: sa + spamdyke + greylisting

Total messages:                Ham:       Spam:      % Spam:   
39676                          31763      7913       19.94%

Average spam score            : 13.31/4.84
Average ham score             : -0.84/4.85

[1] http://www.sourcefiles.org/Log_Analyzers/sa-stats.pl
[2] http://pastie.org/private/bzncofm9e0vhbez8kacnka


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