Email From Google Not All Syncing into ZOHO

Email From Google Not All Syncing into ZOHO

Two Part Question please.

Our company began using ZOHO a few months ago. Since that time, only past emails iised  our google apps company email are recording.  Some are 6  months behind.  

What we need to do is run a report on an account where all email streams are important. Therefore not only do I need to figure out why emails are not all showing but also need to find out once they are recorded, how to have all of them show in a Report.

Thanks!