Address Assignment Question

Jérôme Nicolle jerome at
Mon Jun 20 22:16:22 UTC 2011

2011/6/20 John Levine <johnl at>:
> Hi.  I'm the guy who wrote the CEAS paper on greylisting.


> Greylisting is useful, but anyone who thinks it's a substitute for
> DNSBLs has never run a large mail system.

You're right, greylisting on a large system may not be efficient as it
won't block everything and will eat-up quite a lot of system
ressources. But it's a good start once basic protocol-checks have
already eliminated the 80% amount of bullshit sent from botnets.

My point is : combining server-side checks of different nature is
often enough to avoid the use of RBLs and still provide a goode
quality of service. It probably won't scale to comcast' or AOL' MXs
but it's way better than relying on an external authority for your
corporate or personnal mailserver.

Jérôme Nicolle

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