Delivery Status Notification (Failure)

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

The response was: 550 5.1.1 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. Learn more at https://support.google.com/mail/?p=NoSuchUser f25-20020a2eb5b9000000b0029350a86e14sor1557725ljn.49 - gsmtp