Zitat von Patrick Ben Koetter <p...@state-of-mind.de>:
* Wietse Venema <postfix-users@postfix.org>:Stan Hoeppner: > On 8/23/2011 9:10 AM, Kov?cs J?nos wrote:> > Thanks Ralf! It's amazing how much spam the pregreet test and a good RBL can catch.> > Do you have any data on how many spam emails survived postscreen? > > Overall, Postscreen is no better nor worse at stopping spam than what > we've all been doing via SMTPD for many years. It simply decreases the > number of SMTPD processes required to do so, hence decreasing server > load and allowing more processing of legitimate mail. > > Postscreen is no magic bullet, it's overall "catch rate" being little > different than setups without Postscreen. Agreed. Postscreen's main goal is to reduce mail server load, so that you can postpone that forklift upgrade. Postscreen also stops a few percent of spambots that popular DNSBLs miss, but at this time, that is only a minor benefit.I tend to believe (speculation, not measurement) I can get rid of greylisting, which I dislike because it slows down first mail contact, if I use postscreen.Not because postscreen does the same job, but because it seems to keep the same miscreants away.IIRC I've seen a few discussions on this list that seemed to discuss the topicgreylisting vs. postscreen, but I didn't have the time to read and follow them.I disabled greylisting since I started using postscreen and the spam ratio didnot increase, but the immediacy at which mails from new senders arrive did. Anyone with similiar observations?
No hard numbers but it looks like the massive spam bots time has passed. Already half of the spam we see today is from proper setup MTA server farms in well connected locations routed by a "dirty dozend" of providers. The spam is well targeted (native language) and not illegal in case of law because proper disclaimer from companies located in Belize and the like. For these you are out of luck with postscreen and with greylisting. We still use greylisting because we have a very long first greylist duration with immediate very long automatic whitelist after the first succesful attempt. With this we gave the RBLs we use time to catch the spam bursts and have no delay for the daily business mails.
But as others said: Everyone has his/her own mix of spam anyway. Regards Andreas
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