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:

  vrbka na sanborn.cz
    SMTP error from remote mail server after RCPT TO:<vrbka na sanborn.cz>:
    host mail.sanborn.cz [80.250.8.69]: 501 5.7.1 <linux na linux.cz>... IP 62.36.20.208 refused by the DNSBL bl.spamcop.net
  hejky13 na emile.cz
    Unrouteable address
  augustin84 na seznzam.cz
    Unrouteable address