Retrieving service settings

[Simon Buelens]

I have a Marketplace service and it is installed on some Google Apps domains. It is possible for domain owners to create suborganisations and restrict access to certain services, mine included. 

I was looking for a proper way of requesting these settings, but couldn't find any. The only thing that currently comes to mind is using the provisioning api for each account and check if I can get the user info. If it returns an 401 error, it would mean that account does not have access to my service.

What API can I use to retrieve what users have access to my Marketplace service, properly?