Where does an ubuntu machine get the default domain to append to users when sending mail? Ours is currently sending as firstname.lastname@example.org, while /etc/mailname has mail.example.com set. Should this not be sending as email@example.com? I'm using exim4, and I've dpkg-reconfigure'd it so that the system mail name, and the visible domain name are both set to mail.example.com.
--edited to include mailserver--