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:

  theimer na juli.cz
    SMTP error from remote mail server after RCPT TO:<theimer na juli.cz>:
    host gate.juli.cz [62.168.15.26]: 550 5.7.0 Your server IP address is in the SpamCop database, bye