How Do I Block These Junk Mails

I receive tens of junk mails which I delete everyday. Many of them are downright stupid. I don't know how the writers of these mails thinks we would fall for many of their hare-brain offers. Initially I used to be amused at the stupidity of these writers but of late, I am angry as these mails increases everyday. Does anyone have any idea how I can stop these stupid mails from getting into my mail boxes. I have four mail addresses because of the antics of these irritating scammers.  I still receive their unfortunate mails in all my mail boxes. I am fed up. 

Some of the have an unsubscribe button at the bottom (as if you subscribed in the first place). You can try that.

Alternatively if the junk mails do not find its way into your inbox, you don't have to read them. If they do, then you're probably registered to too many forums, etc.

I thank you all for your advice. I'll try some of them most especially the$4 mail services. I think you are right that I have subscribed to too many services. I think I've now learnt  my lessons.