I have the number of mail rules for the stuff like this. While you can do this in any client, I also keep thunderbird client open constantly on one of my media

I have the number of mail rules for the stuff like this. While you can do this in any client, I also keep thunderbird client open constantly on one of my media servers because it provides some features other rule machine engines do not, like an option to block by any header. I successfully blocked legitimate spam that way, the one that was somehow passing gmail. This works perfectly. Another way is to use throw away email address per subscriber. You can for example use mailcare :)