It's free, you don't have to do a thing ( apart from put any senders mistaken as spammers into the "good" filter) and NO SPAM in your O/E 6 inbox, NONE.. ZERO.. They mail you regarding any they aren't sure of.
I have used Mailwasher for a long time it reads your email subject line before it come to your box you then have 3 options delet blacklist or return to sender (Bounce) its brilliant, Type mailwasher into Google as I cant think of the address
prof. - only one problem with sending it all back: the "from" address is rarely, if ever, a real address and bouncing mail only clogs up systems more and more. In the unlikely event that the address is real, it will likely be an innocent person who has had their address hijacked.