Mail System Error - Returned Mail

[Mail Delivery Subsystem]

This message was not delivered due to the following reason:

Your message could not be delivered because the destination server was
not reachable within the allowed queue period. The amount of time
a message is queued before it is returned depends on local configura-
tion parameters.

Most likely there is a network problem that prevented delivery, but
it is also possible that the computer is turned off, or does not
have a mail system running right now.

Your message could not be delivered within 3 days:
Host 49.244.204.173 is not responding.

The following recipients did not receive this message:
<redhat-cz na linux.cz>

Please reply to postmaster na linux.cz
if you feel this message to be in error.