Re: [Sqlgrey-users] Backup MX servers

[Michel B. <mi...@bo...>]

Le Jeudi 16 Juin 2005 10:16, Lionel Bouton a =E9crit :
>
> >>Are we seeing an increase in the number of spam sending MTAs that don=
't
> >>give up on the first attempt?
> >
> >I believe so. And I also have seen a growing number of spams that retr=
y
> > after about a minute. But not longer. Which means that greylisting
> > duration should probably not being set < 2 minutes.
>
> I've seen this too. The new default in 1.6.0 will be 5 minutes instead
> of 1 minute (I've only witnessed retries from real MTAs after at least =
6
> minutes).

Yes. I use 5 minutes myself. I've seen that most legitimate servers have =
an=20
average retry time around 19 minutes, so it doesn't hurt much increasing=20
greylisting delay a little.

Of course spammers may still increase their retry delay, but the more the=
y=20
will increase it, the more burden it will put on their systems, the more =
it=20
will slow down their throughput, and the more chances it will give that t=
heir=20
IP gets into some blacklists before they retry. So that's all benefit=20
anyway ;-)

BTW Lionel, have you made your decision about whether to put throttling i=
n=20
1.6.0, and which algorithm to use ?

--=20
Michel Bouissou <mi...@bo...> OpenPGP ID 0xDDE8AC6E