The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'admin@xxxxxx.org'. Subject 'test', Account: 'was123@xxxxx.com', Server: 'mail.xxxxxx.com', Protocol: SMTP, Server Response: '554 5.7.1 <admin@xxxxxx.org>: Relay access denied', Port: 25, Secure(SSL): No, Server Error: 554, Error Number: 0x800CCC79
Host or domain name not found. Name service
error for name=localdomain type=A: Host not found
So, you said you installed using install.sh, right? I’m confused how you have all of these misconfigurations! None of this should have been possible (well, there is that one bug on Ubuntu where Dovecot doesn’t get it’s plain password directive set right, but all the rest of this should have been right after the install).
Anyway, this problem is happening because your box doesn’t have a correctly configured fully qualified domain name. The install script should have refused to run in such a circumstance.