Re: [exim] greylisting

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Author: Paul Johnson
Date:  
To: exim-users
Subject: Re: [exim] greylisting
On Wednesday June 15 2005 2:16 pm, Mark Nipper wrote:
> On 15 Jun 2005, David Woodhouse wrote:
> > On Wed, 2005-06-15 at 18:43 +0200, Steffen Heil wrote:
> > > I don't want to take this into account, since I do greylisting
> > > at RCPT time.
> >
> > But that presumably means you're doing greylisting
> > unconditionally. It makes a lot more sense only to do it for mail
> > which is actually considered suspicious for some reason.
> >
> > Otherwise you just end up delaying a lot of good mail for no
> > reason.
>
>     Isn't that really kind of the whole point?  If the mail
> is legitimate (ideally), the remote side will resend in a bit and
> the tuplet will be recognized as valid at that point for some set
> period of time (few weeks to months normally).


That's more or less Debian's idea of it. greylistd (which provides
greylisting for exim4 in Debian) has a default greylist interval of
60 minutes and saves tuplets for 2 weeks. It works out really well
after a day or two.

>     Outside of the initial delay for the first message, any
> regular e-mail traffic will flow normally as it should.


It does at ursine.ca, so there's at least a small case-in-point.

> You have to keep an eye on known mailing list hosts of course
> whenever they change the envelope sender for each message sent from
> a list and just add the exception as needed.


I haven't had a problem with mailing list hosts, they get whitelisted
by greylistd just fine on their own.

--
Paul Johnson
Email and Instant Messenger (Jabber): baloo@???
http://ursine.ca/~baloo/