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:

  svacink1 na centrum.cz
    SMTP error from remote mail server after RCPT TO:<svacink1 na centrum.cz>:
    host cbx.virusfree.cz [31.7.241.26]: 554 5.7.1 <svacink1 na centrum.cz>:
    Recipient address rejected: Access denied, user does not exist
  mates.siroky na centrum.cz
    SMTP error from remote mail server after RCPT TO:<mates.siroky na centrum.cz>:
    host cbx.virusfree.cz [31.7.241.26]: 554 5.7.1 <mates.siroky na centrum.cz>:
    Recipient address rejected: Access denied, user does not exist
  klokann na centrum.cz
    SMTP error from remote mail server after RCPT TO:<klokann na centrum.cz>:
    host cbx.virusfree.cz [31.7.241.26]: 554 5.7.1 <klokann na centrum.cz>:
    Recipient address rejected: Access denied, user does not exist