[Mimedefang] Justifying greylisting to management

Kevin A. McGrail kmcgrail at pccc.com
Sun Feb 26 11:11:21 EST 2006

>> In my testing, I found that greylisting had too many false-positives
>> causing important and even critical mail to be unacceptably delayed.
> Really?  That's quite the opposite of my experience.
> Greylisting is good IF you turn off greylisting for hosts known to retry
> (we do that for 40 days: If a host retries, we no longer greylist that 
> host
> for 40 days.)
> That greatly reduces delays because mail servers that you often correspond
> with quickly move on to the "do not greylist" list.

Good Point. The use of a multi-month "whitelist for hosts known to retry 
properly to disable greylisting seems like an excellent fix that would 
probably solve 75% of the issues I was detailing previously (hazarding a 
guess here).

I just don't know if that 1 email that got delayed X number of hours from a 
non-whitelist host wouldn't be the proverbial spine breaking straw and have 
a feeling it would occur here and greylisting would have to be 100% removed 
because of 1 FP email delayed.


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