In the mail log 
menu, you have an overview of all the emails that have been sent by all sub resellers and companies under you.
The following information is shown for each email:
Date: the date the email was sent.
Email: the type of email. See templates.
Recipient: the email address of the recipient.
Status: the status of the mail.
Searching and Filtering:
✔ Type in the email of the user you want to search for in the "Search recipient" field. The list will be narrowed with each letter you type in.
✔ Click on Filter to filter for Email type, and delivery Status.
✔ Click on Filter, then Reset to reset the filter.
✔ Control how far back in time you want to search for emails with the dropdown menu next to "Show for". Default setting is 7 days.