I've been getting lots of commercial emails from places I bought something from once or twice, and I finally went through and unsubscribed from all of them! Now they won't keep clogging up my inbox. Whew! It took about five minutes to unsubscribe from about 20 lists, and I wish I'd done it sooner instead of being annoyed every time I'd get another ad.
(Note, these were not spam emails, where you should never, ever hit unsubscribe. Instead they were real companies like Costco.)