Everything looks correct in the server behavior settings. I tried to telnet to the smtp server mail.ycdevelopment.co.uk on port 25 and got a "Cannot connect to server" error, so I would start by checking to make sure that is the correct smtp server address.
If it is the correct address, then the smtp server is refusing to relay the email for some reason, you will need to contact the host to look into the smtp server error logs to determine why the email is not being relayed.