How do I validate email in PHPMailer which does not exists?

I want to know how to validate emails entered in the input box are real and exist, and if the provided email does not exist I want to throw an error.

What I mean to say is when I enter this email “[email protected]”(doesn’t exist) and send it, I receive from mail delivery subsystem

but PHPMailer doesn’t throw any error simply moves forward, do’s what the next line in the program is.