Change password FROM spark on AD integrated openfire server

Hy friends,
I have an internal environment with 1 openfire server integrated on an w2k8 r2 domain and 250 machines witch I can manage clients and passwords from the domain. But I either have many external locations that log to my openfire server, but that locations are not at my domain, so, I’m trying to give the permissions for that clients (witch machines are not at my domain) to change their own passwords from the spark client, but the user get the denied permissions message.
Someone knows if it possible to configure openfire/Active directory so the users get the permissions changing passwords from spark clients?
Thantks a lot and sorry by my bad english