squarebear (what a nice nickname) is right, it's mostly likely spam emails. simply ignore them and delete everytime you get them. or you can use some email filter to deal with spam.
don't ever open spam emails and don't reply asking for unsubscribe, cos these ways you let the spammers know that your email address is in use and they can send more messages to you. that's my sad personal experience.
to learn more about spam you can read
How to protect from Spam article.