Milter-greylist

>The solution you suggest is performed after the mail server accepted the 
>message. You want to delete a message from a mailbox because the sender is 
>in a blacklist. But if the blacklist is wrong, you delete a valid message 
>without a notification.

Why is notification impossible when deleting previously accepted messages as 
I suggested? Why not:

- ISP receives a message for user
- sender address appears on blacklist an hour later
- ISP rejects THEN, with notification

Also, if you're assuming the blacklist is unreliable, then why did you 
write:

>I'd rather see [black list filtering done] at the MUA (Mail User Agent,
>outlook express in your case) level.

I also don't understand why automatically updated blacklists should 
generally be unreliable. When do legit addresses send email to honeypot 
addresses?