Activity Report (Emails sent) not accurate; how to...?

Activity Report (Emails sent) not accurate; how to...?

Hello, I created a number of reports to reflect rep activity, using various time slices: 
Tasks, Events, Calls - current month, previous month, YTD, etc.  

Emails Sent - various time slices as above. 
The concern is this: the Emails Sent report does not capture emails sent from Zoho by all users. 
Indeed it only captures one or two, while the actual volume of emails is in the dozens or higher. 

There is nothing I can find in the settings that would filter by user, or include all. 

Can you assist? 

Thanks, 

Ed
+1 781 492 7638 USA East