How to reset Qmailadmin password

I was handling 2 website include their mail and web
and i forget one of the qmailadmin password
geez what a troublesome ..
I was confiused for a while since i forget the password
but then i look for it on google
i love u google ..  :-*

and i found howto reset it ..
with condition u have root password on u

just type “this/home/vpopmail/bin/vpasswd postmaster@testdomain.com"

and u will be promt with this Please enter password for postmaster@testdomain.com:
enter password again:

and there you go the password was reset to the one you just set ..