When my spam filter detects possible spam, I want to give the sender a chance to correct whatever might need correcting and try again, or write me a letter, or at least know that my mail server didn't accept the email. But I don't want a bounce message being sent to a wrong address that a spammer forged. I also don't want to manually review email that was detected as spam because there's too much. What I need is a spam filter that will bounce an email that was detected as spam only when the email was authenticated with something like DomainKeys or SPF.

The closest thing I found was this message about a 2005 version of the Courier Mail Server, but it doesn't make it clear whether it lets you bounce only email that's authenticated or whether you have to bounce all spam and the authenticated spam goes to the authenticated address. I want to bounce only authenticated spam, and have it go to the authenticated address. In the current documentation for Courier Mail Server I couldn't find anything about the function I want, but it's possible I looked in the wrong place.

I want this functionality as an end user, not an administrator. If I can find a product that allows such bouncing, I'll look for an email service provider, web hosting service, ISP, or whatever, that offers it. I don't want to create my own custom filter.

Anyone know of a product or service with such a spam bouncing feature?

No you don't! This just tells genuine spammers that there is something at that address and they'll focus their botnets on you.

This is a no-win situation. The best you can do is direct suspect mail to a special letterbox. Anyone you know who ends up there can be properly LARTed. Spam filters are usually good at letting genuine mail through... when the sender actually writes a message other than "get a load of the attachment".

Of course, if you doctor wants to email you your viagra prescription, that could be a problem

I put my email address in plain text on my homepage anyway, and until a few days ago I bounced all spam whether or not it was authenticated. When I switched from bouncing to forwarding it to my own mailbox I think I saw about 100 spams per day, which I didn't want to look through, so now I delete the spam. I care more about not missing non-spam, even if it comes from an email address that I don't know about and can't whitelist, than not getting more spam.

Trust me: any replying to spam will put that count past 1000 a day quite fast.

I was trying to say that I tested that. Right after I stopped bouncing spam (which I had been doing for years) I got to see how much spam I was getting. I think it would have amounted to a maximum of 300 per day, but it's hard to say because I don't remember the exact hours when I was letting it pile up, or exactly how many hours, but I know it was at least overnight. When I bounced spam and deleted it, I only saw a few spams per day. If I started bouncing only authenticated emails that were detected as spam, I'd probably get even less, though most people would probably get more.