Update Free/Busy

[Fabio]

Hi all,
I'd like to know if there's a reg key to change so I can update the
free/busy information of all the users via group policy.
I've set the free/busy info visible for 6 months via policy but if the users
don't open their outlook with the /cleanfreebusy option nothing is update.
Do you know a way to open outlook with the cleanfreebusy option in an
enterprise environment? There is only updatefb.exe tool or others things?

Thanks in advance