I had registered for another program two days before when I discovered Chrysanth Mail Manager. Easy to configure and easy to work with, the program lets you define the filters you want to stop recurrent expressions in spams, lets you allow or block specified senders (email addresses and / or domains)... You can view the content of the emails before you download them, bounce an email, delete the spams directly on the server... Clearly one of the best choices you could make if you have to deal with numerous spams. Most of all, it's not expensive and the interface is really good. Just download the evaluation version, you'll see by yourself !

Does what it says on the box. Has a couple of niggles, but improves with each up date.
I've used many anti spam tools - CoffeeCup Spam Blocker, MailWasher Pro. But Chrysanth Mail Manager does the same job a lot cheaper.