Mail delivery failed: returning message to sender

[Mail Delivery System]

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  ryzask na amateri.cz
    SMTP error from remote mail server after RCPT TO:<ryzask na amateri.cz>:
    host aspmx.l.google.com [173.194.76.26]: 550-5.1.1 The email account that you tried to reach does not exist. Please try
    550-5.1.1 double-checking the recipient's email address for typos or
    550-5.1.1 unnecessary spaces. Learn more at
    550 5.1.1  https://support.google.com/mail/?p=NoSuchUser d3si20081wru.387 - gsmtp