This error means that the smtp server is not accepting the connection for some reason, you will need to work with the host to determine why the smtp server is not allowing connection to be made. It could be that the ip address (109.104.92.194) is being blocked, or the from address could be blocked, or the username and password could be the problem.
At this point UE is trying to hand off the email to the smtp server to be relayed, but the SMTP server is not allowing it to happen, this is an issue with the server.