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:

  kelda1993 na seznam.cz
    SMTP error from remote mail server after RCPT TO:<kelda1993 na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  kyle1997 na email.cz
    SMTP error from remote mail server after RCPT TO:<kyle1997 na email.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  makrofonka na seznam.cz
    SMTP error from remote mail server after RCPT TO:<makrofonka na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  asdasd na aseas.cz
    Unrouteable address