It might sound simple, but by clicking on the subscribe link at the bottom of newsletters and advertising emails, you can keep your inbox tidier.
Spam filters will do a good job of keeping the nasty stuff away from you. Good Spam filtering remove viruses, malware, fishing attacks.etc and spam emails. They wont stop emails coming from sites you have subscribe to and left your details.
So that leaves you to either ignore the email or unsubscribe. Just click the link and unsubscribe.