Spam gmail

My problem with Outsurance is the amount of spam gmails that they send me. Where do they get my private gmail from? Not from me. I do not give out my private gmail address to anybody unless I want get them. I am not a client of Outsurance so what gives them the right to find out my private gmail address and send me all those spam gmails? It is an intrusion on my privacy. If I was a client sure, send me gmails to keep me updated. But if I am not a client then please me alone. I am not intereseted in Outsurance. Your gmails are spam and a pain. It gives you a bad name and does want people to join you. I have no unsubscribe button on my phone. So just please leave me alone and all the other people you pestering.