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:

  support na thebat.cz
    SMTP error from remote mail server after RCPT TO:<support na thebat.cz>:
    host mail.thebat.cz [93.185.104.7]: 550-rejected because 62.36.20.210 is in a black list at b.barracudacentral.org
    550 http://www.barracudanetworks.com/reputation/?pr=1&ip=62.36.20.210
  krtecek na kalhotky.cz
    SMTP error from remote mail server after RCPT TO:<krtecek na kalhotky.cz>:
    host post.bigweb.cz [80.79.17.138]: 554 5.7.1 <krtecek na kalhotky.cz>:
    Relay access denied