No route found to domain Xxxxxx from server Notes1/domain. Check server, connection and domain documents in name and address book.
The server doesn't understand how to interpret the e-mail address. It either doesn't recognize the domain as an Internet mail address, or else it just doesn't know how to send Internet mail at all (that would be an admin issue).
Are you maybe addressing your e-mail to abc@Xxxxxx as opposed to email@example.com? Can you send to the same address using the Notes mail application?