Delivery Status Notification (Failure)

Address not found Your message wasn't delivered to replytounsub@google.com because the address couldn't be found, or is unable to receive mail. LEARN MORE

The response from the recipient enterprise administrator was: The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. For more information, go to https://support.google.com/mail/?p=NoSuchUser