Milter-greylist

I don't know if spammers really actually doing this but in my last job 
where we send out newsletter mails (for
a local amazon-like webshop, user agreed to receive this letters...) to 
around 300tsd customers we used the
return code (over a longer periode) to disable the newsletter for this 
addresses.

Also when I'm searching through the maillog of an qmail server which 
doesn't accept mails for non-existing users
I can see that a stupid DSL-account spammer only retries the really 
existing email addresses (different spams)
over a longer periode. This selfmixed firstname.lastnames addresses 
which are not existing don't appear here twice
while the really existing email addresses appear in every spam run...

manu@... schrieb:
> Andreas Unterkircher <unki@...> wrote:
>
>   
>> Only a short note on this. When you only accept mails for existing users
>> and return a error for all
>> non existing users, it's easy for a spammer to checkout which email 
>> addresses actually exist. 
>>     
>
> Do they really collect addresses this way? It sounds rather unefficient
> (compared to parsing web sites)
>
>