There is no method to actually stop them being sent - I have the same problem, I have hundreds a day. The best thing you can do is get a decent e-mail program with a spam filter - although if you are using webmail (Gmail, yahoo, hotmail, etc) then these should have built in filters you can enable.
Not opening them is great - if you open them, click links etc then they may have confirmation the email address is 'active' so they'd send more and more emails.
Perhaps you could make a new email address. Make sure you never publish your email address online if so - that's the primary way for spam bots to pick your email address up.
Hope I'm of some help.