If you send emails to people who haven’t invited you to do so, you could be breaking the law. There’s a law called the CAN-SPAM Act. Which stands for Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003.This Law regulates commercial emails.
This law gives people the right to unsubscribe to any emails they don’t want. So if somebody asks you to take them off your list, you not only want to do that because it’s good business, but because you may be subject to fines if you don’t do it. And the fines are per email violation, so they can add up fast.