Determining Archive method

We have been doing some searches of our archives to confirm that the policies assigned are being configured as designed.  Our current policy states that only mail greater than 6 months old will be archived.  But we were doing a pilot of desktop policies and allowing the store button.  When we search the archives we do see messages which do not follow the policy, is there a way to determine the methodology used to archive the message.  Was the button used or not?

Thanks

Paul