Am 28.03.2015 um 12:04 schrieb David Jones:
I know that but I choose to use the "traditional" method in the Postfix smtpd_recipient_restrictions so I can specify the order. I have such a high volume of mail for more than 100,000 mailboxes, I want to check in a specific order using my local rbldnsd feed to prevent abuse of other RBLs further down the list
the problem with this approach is that with each RBL you raise the false-positive rates extremely, until now i did not see any RBL without FP be it Zen, Barracuda or Spamcop
most caused by fools reporting mails they subsribed to as spam instead unsubscribe, frankly i got recently even two AOL feedback loops including the original message where customers of our ustomers reported there monthly e-bill including the bill itself as spam
the same for digest services (Pyzor, Razor, IXHASH)with postscreen-scoring you can avoid that completly by not giving any RBL the power to reject a mail while at the same time add a few very false positive prones with a low score - the result is you block much more spam on RBL level with way less complaints and given that "postscreen_dnsbl_ttl = 10m" even applies to RBLs with a TTL auf just a few seconds (Spamhaus) your total dns queries could go down
another thing is performance: "smtpd_recipient_restrictions" is sequential while postscreen asks all RBLs parallel, if one or more have a timeout it don't block, they are just not taken into account at that moment, when you have enough RBL's the result is still good
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