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:

  dknourek na iris.cz
    SMTP error from remote mail server after initial connection:
    host mxavas.forpsi.com [81.2.195.200]: 554 cmg11.fe.forpsi.com cmgsmtp NYYnmEBE2PRkR Connection refused from 62.36.20.208.