Milter-greylist

>> Why should I have to download spam which my ISP knows is spam??

>Because you can never be sure a DNSRBL is reliable. The ISP suspects the 
>message is spam, should the mail be deleted?

Excuse me, but ARE ALL BLACKLISTS UNRELIABLE? That's what you're suggesting.

I never talked about DNSRBL's, and I have no idea why you keep harping on 
them.

If blacklists in general are unreliable, then fix your website, since it 
implies that it's appropriate to use them:

"If spammers ever try to resend rejected messages, we can assume they will
not stay idle between the two sends (if they do, the spam problem would just
be solved). Odds are good that the spammer will send a mail to a honey pot
address and get blacklisted in several real-time distributed black lists
before the second attempt."

-- http://hcpnet.free.fr/milter-greylist/

Your posts also indicate black lists are reliable:

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

If a black list isn't reliable, why use it at ANY level??

You also wrote:

>I do use a blacklist, but it's a manual one. I blacklist the netblocks for 
>which I still get spam and for which no abuse address works.

Are you using an unreliable blacklist? Why??