Restrict Outlook Anywhere

Hi Everyone

Does anyone know how you can use the F5 to provide external access to Outlook Anywhere to a specific group op people based on and AD security group.

I have been asked to allow external access to our Exchange 2013 servers which involves publishing Outlook Anywhere (RPC over HTTP) to the internet.

I cannot see any way to restrict this in Exchange so it is an all or nothing setup which I am not comfortable with and would prefer it if I could restrict access to a select few.

I tried a basic Access Policy with iRULES (This worked for OWA) but the rule never gets triggered. From what I can tell, although it is HTTP - it goes not have the same headers so the ap/irules do not work.

Would really appreciate your help..

Regards

David