[AusNOG] Greylisting in an ISP / Hosting Environment

[Trent Lloyd]

Andy,

On 04/05/2009, at 4:01 PM, Andy Davidson wrote:

>
> On 27 Apr 2009, at 02:33, Shaun Ewing wrote:
>
>> My advice is that if you deploy greylisting, then you need to have
>> at least
>> one MX that does not use it.
>
> If you do this, then it means that the positive effects of greylisting
> are removed, because there's a way in for spammers that does not get
> slowed down.
>
> I use exim and only greylist borderline spam.  This way I get most of
> my legitimate email straight away and only spam suspects get slowed
> down.

Unfortunately that approach would kill one of the benefits of  
greylisting.

Most implementations do it before the data portion, and thus you save  
the traffic of being sent the email, and processing it with your anti  
spam software.

(Not saying it isn't feasible or useful, just making a point)

Trent