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:

  rybnicek na teplarna-cb.cz
    SMTP error from remote mail server after end of data:
    host mail.teplarna-cb.cz [62.168.46.211]: 554 5.7.1 This message has been blocked because ASE reports it as spam.
  kowboj1 na seznam.cz
    SMTP error from remote mail server after RCPT TO:<kowboj1 na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  lukilin na seznam.cz
    SMTP error from remote mail server after RCPT TO:<lukilin na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.
  polo6ntuning na seznam.cz
    SMTP error from remote mail server after RCPT TO:<polo6ntuning na seznam.cz>:
    host mx1.seznam.cz [77.75.78.42]: 550 5.1.1 Sorry, no mailbox here by that name.