In many parts of the world (including the US) it’s illegal to send unsolicited bulk email. To legally send bulk emails and respect anti-spam laws like the CAN-SPAM act, your email contacts need to be 100% opt-in. This means they’ve given explicit consent to receive emails from you via an email signup form or other subscription method. Never use purchased lists. On top of that, the email content should always match the purpose stated on the sign-up form and contacts must have the option to unsubscribe at any time.