So you have had an email account for a good few years and over time you have been receiving more and more junk that you may have or may not have signed up to. Its not really SPAM since you signed up to it at one point and time.
Some solutions to your email problems is to start using this great service called Unsubscribe https://www.unsubscribe.com
There are plugins for almost every email checking firefox, gmail, outlook, thunderbird. Download plug for specific platform by visiting website above and get unsubscribing
Let me know what you think