Milter-greylist

On Oct 7, 2009, at 3:46 PM, philippeake wrote:
> Very few spammers still used dedicated systems to send out their  
> wares, most now use bot farms.
>
> This means that they will be sending via real MTAs, which will retry.
>
> Looking at my logs over the last two days I see this:
>
> # grep "Greylisting in action" mail | wc -l
> 1234
> # grep "delayed for" mail | wc -l
> 1234
>
> So every email delayed by greylisting was eventually re-sent and  
> accepted.
>
> Most SPAM was blocked by RBLs, that which passed (the 1234 above)  
> then went on to SpamAssassin, which trashed around 1,210 of them as  
> SPAM.
>
> Greylisting contributed ... zero.
>

Did you ever invest time to see how those spam mails actually where  
sent to your MX?
If they are sent thru a "valid" mail relay, greylisting won't help  
you. That's not exactly any new news...

We use greylisting, and it's still very useful. But on the other hand,  
we don't like the idea of using RBL to reject mails "hard" (5.x.x) as  
you are doing.

/P