Your message was undeliverable due to the following reason:
Your message could not be delivered because the destination server was unreachable 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 was not delivered within 4 days: Mail server 18.104.22.168 is not responding.
The following recipients did not receive this message:
Please reply to firstname.lastname@example.org if you feel this message to be in error.