spam filter control protocol

There are many different spam filters. Some of them can work independently of your other software, acting as the mail-server, filtering and forwarding the mails to your real server. Others are plug-ins or extensions to your server. And, still others, are embedded components of or plug-ins of your e-mail client. Not a one of these is perfect, and getting the best performance out of it often requires some user feed back. "No, my grandma's recipe for the family secret cookies is not spam.", "Yes, this offer for free viagra is spam." for example. So it seems to make sense that what is needed here is a common protocol for an e-mail client to connect to a spam filter, be it through some IP-based protocol, COM-like interface, or what-have-you, to handle such tasks in a filter-independant manner, so as to give each of us our choice in spam filters, without sacrificing the almighty ease-of-use.