On Debian systems config.hostname directive should change /etc/mailname
in order to prevent problems with default mailer trying to contact
default vm's name.
I don't use `activated` here because I'd really like to optimize
performance as much as possible, and loading files from disk is
generally slow. So instead of using `activated` I load the file at the
last possible moment which is when the exact class is being requested.
I don't think many people will do this outside of the core, and I'm not
too concerned.
Mitchell Hashimoto
Bob Maerten