Mail System Error - Returned Mail

The message was undeliverable 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 configuration  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 4 days: Server 65.120.148.18 is not responding.

The following recipients could not receive this message:
<haproxy#formilux.org>

Please reply to postmaster#mir2.org
if you feel this message to be in error.