If you are trying to run jabberd on a Gentoo Linux installation with the portage package, take care to uncomment the <mod_register> and <register> tags in the /etc/jabberd/multiple.xml configuration file.
Or else the registration of new users will certainly be rejected with this error message:
"If it´s there and you can see it - it´s REAL
If it´s there and you can´t see it - it´s TRANSPARENT
If it´s not there and you can see it - it´s VIRTUAL
If it´s not there and you can´t see it - it´s GONE!" nach Roy Wilks, 1983