Stopping junk emails is not as simple as hoping they magically disappear. Of course, after signing up for the nth website which offers free beer or free coupons, do not expect to never receive promotional emails about their products or even other sorts of spam. Stopping junk email first requires prudence. There are many steps to avoid it and prudence is ultimately key to it.
To minimize spam, do not just put your email address just about anywhere. Do not put it up in any random website, even if you regularly subscribe to the said website. Anything put up on the world wide web is fair game and can thus be spammed. Be careful in putting your email address in an easy recognizable form. This increases the chances of it being spammed.
Be sure to read all the terms and agreements of the website you sign up to. Esepecially websites which aim to promote certain products, these websites are bound to send you promotional emails every once in a while. Some of them more often others. Be sure that you know what you are getting yourself in to.
Never ever reply to any spam. This only opens up the possibility of you receiving more spam than necessary. As always, prudence is key to avoiding these annoying emails.