This is a very common error.
It means that DeskNow cannot deliver your message to the remote mail server.
There are several possible causes for this error.
1) Your internet connection is down.
Make sure your internet connection works properly.
2) There is a firewall blocking outgoing connections using the SMTP port (25).
If this is the case, ALL the outgoing messages will encounter this error.
The firewall could be in your LAN, or it could be set up by your ISP. Some ISP for residential users block port 25 to fight spam.
check that your firewall is not blocking port 25 outgoing. Configure your firewall accordingly.
If you still get this error with every message, then it is probably your ISP blocking he SMTP port. Contact your ISP asking them more informations, or simply configure DeskNow to forward outgoing messages through your ISP's SMTP server. To do this, log in as admin, go to Administration/Mail, and see the option "SMTP Forwarding" under the section "SMTP Outgoing"
3) The remote mail server is down, unreachable from your network, or busy
This is typically the case if you get this error only with a mail server, but can usually send email fine to other domains. This problem can happen to any servers, even to servers of big public services like Hotmail or Yahoo.
There isn't much that you can do in this case. Try and contact the administrator of the remote server if you can. Try to send an email from Hotmail or Yahoo, to check if they can connect to the remote server.
In any case, DeskNow typically retries the delivery after a few hours (depending on your configuration settings).