Re: What is GreyListing

[Michael Loftis <mloftis@modwest.com>]

It's not at ll like challenge response.  Challenge response sends email tot 
he senders/humans asking them to confirm.  We're just asking systems to act 
like a noirmal mailserver during greylisting, which is 4xx, retry later. 
It won't work forever.... eventually spambots and virusbots will catch on 
and start retrying after being 4xx-ed but implementing it now makes you 
just harder than your neighbor to break into so for the time being they'll 
mostly leave you alone.



--On Tuesday, July 20, 2004 12:31 -0700 Paul Johnson <baloo@ursine.ca> 
wrote:

> Christian Hammers <ch@lathspell.de> writes:
>
> > Hello
> >
> > On 2004-07-20 Russell Coker wrote:
> > > (host mail3av.westend.com[212.117.79.67] said: 450 <ch@lathspell.de>:
> > > Recipient address rejected: Greylisted for 300 seconds... (in reply to
> > > > RCPT TO command)) ch@lathspell.de
> > >
> > > Christian's mail server is broken.
> >
> > Err, no. It's not a bug it's a feature :-) Called "greylisting".
> >
> > In opposide to normal black- and white-listing here postfix has an
> > additional policy daemon that checks if the tripel "sending ip, from,
> > to" is already in the database and if not, reply with a 450 aka
> > "temporary(!) failure" code and take note of it.  If it's a real
> > mailserver and not a trojan-winXP-desktop then it will try it again in a
> > couple of minutes. If it does the above tripel will be whitelisted for
> > the next days/month/whatever.
>
> This sounds suspiciously like (dangerously stupid) challenge-response
> systems.  How does this differ?



--
Michael Loftis
Modwest Sr. Systems Administrator
Powerful, Affordable Web Hosting