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:

  renata na email.cz
    SMTP error from remote mail server after RCPT TO:<renata na email.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  motorbikerevue na seznam.cz
    SMTP error from remote mail server after RCPT TO:<motorbikerevue na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  jarda.vapno na seznam.cz
    SMTP error from remote mail server after RCPT TO:<jarda.vapno na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  adam.cermak na seznam.cz
    SMTP error from remote mail server after RCPT TO:<adam.cermak na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  stexia na email.cz
    SMTP error from remote mail server after RCPT TO:<stexia na email.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.