Mail delivery failed: Incoming mail blocked.

[Mail Delivery System]

This message was created automatically by mail delivery software.

A message that was to be delivered to your mail could not be 
delivered to one or more of its
recipients. Attached is the incoming mails that were blocked from 
entry your mailbox.
This is a permanent error. The following address(es) failed:

    all relevant MX records point to non-existent hosts

Action: failed
Final-Recipient: linux na linux.cz
Status: 5.0.0

You can click on the release button in the attached for the mail 
to be delivered to your mailbox.