greylisting?

[shuttlebox]

On 4/16/06, Alex Neuman van der Hans <alex at nkpanama.com> wrote:
> I have set up greylisting for companies that receive 30 messages per day
> and want to receive within 3 minutes. Greylisting for 30 seconds works,
> and gets rid of a lot of spam. GREET_PAUSE also works great.

But you can't control how quick they will try to resend. Even if you
set it to 1 second most MTA:s will wait a lot longer to retry, like 15
minutes, and many users complain about that. Of course you can
whitelist but only after having complaints. I try to make it smoother
by checking the logs for the top domains we get mail from and put them
in the whitelist right from the start.

I don't know if I misunderstood earlier posts about huge number of
connections being used by greylisting. That is more true of the
greet_pause method than greylisting which instead can use a lot of
memory for the database.

I use a mix of greet_pause and greylisting at several customer sites
and for me greylisting is a lot more effective but you have some
explaining to do from time to time. Greet_pause is more transparent to
the users and seems to block mostly computers that should not send
mail anyway.

--
/peter