Office 365 offers some really great stats and servie information but sometimes falls short on the specifics.
For example, the dashboard will show you the number of inactive users over a period of time but now which users those are. For that, you need Powershell.
Find out more here:
Came across an issue today with a client using Google Apps & BESX- new users weren’t appearing in the GAL even after rebuilding the address book files. Turns out the issue was down to BESX using LDAP rather than MAPI to search for users; which was fine for our on site users in AD but not the field-based GA-only users.
Check out this link for info on how to fix the issue: