RE: Greylisting

Jon Reynolds wrote:
> I am considering greylisting as yet another layer for spam. I have
> been reading the pros and cons and have a list of the servers that
> will not try a resend. I can easily white list those servers when the
> time comes, but I was wondering if anyone else uses greylisting and
> their experiences with it.
>=20
> How many IP's or domains have you actually had to white list? Has it
> been effective at stemming the tide of spam? Is it recommended or is
> there something I missed in my reading that makes it a bigger headache
> than creating a new cf for spamassassin?
>=20
> Thanks for any advice,

I'm not greylisting, but I did implement greet_pause. If you're using
sendmail 8.13 you might add:

  FEATURE(`greet_pause', `10000')dnl

to your build. It provides some of the functionality of greylist but
was already available. I saw a dramatic drop off in the amount of spam.
What it's doing is putting the sending MTA "on hold" so to speak.
Legitimate MTAs handle it just fine. Spam machines don't have time to
wait so the connection is dropped and never picked up again.

I whitelisted a couple of domains in /etc/mail/access but didn't spend
much time on it after the first couple days. Nobody's called
complaining their mail is being rejected, and it's been months since I
implemented it.

HTH...

...Kevin
--=20
Kevin Miller Registered Linux User No: 307357
CBJ MIS Dept. Network Systems Admin., Mail Admin.
155 South Seward Street ph: (907) 586-0242
Juneau, Alaska 99801 fax: (907 586-4500
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Received on Wed Jan 4 14:31:08 2006