Cannot block a nuisance website from emailing

I had a problem some months ago and my filters were compromised, so I was put on hundreds of mailing lists from commercial sites all over the world. I still get a new one once in a while, but there's one persistent one that doesn't have an 'unsubscribe' option and--despite repeatedly marking it as 'Spam' and trying to block it via a filter STILL keeps getting thru, generally an email or two about their products per day. Is there any way to report these people as a nuisance or block them totally? The problem isn't earth-ending but it is Vexing. Thanks.