Mail delivery failed: returning message to sender

[Mail Delivery System]

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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:

  igor.pipik na educanet.cz
    SMTP error from remote mail server after RCPT TO:<igor.pipik na educanet.cz>:
    host aspmx.l.google.com [108.177.15.26]: 550-5.2.1 The email account that you tried to reach is disabled. Learn more at
    550 5.2.1  https://support.google.com/mail/?p=DisabledUser y18si21935389wrt.551 - gsmtp