How to create a report containing the average message size per user (KB) and average messages per user for a given time period?
Open MessageStats Reports and perform the following:
1. Click "My Reports" in the left panel and "File" | "New Custom Report" in the right panel.
2. Click "Next" in the wizard and select either "Mailboxes - User Volume Received Details" or "Mailboxes - User Volume Sent Details". Continue by clicking "Next".
3. In the "Fields" tab, there are fields for Internal and External Average Size and Messages. Also be sure to include the DisplayName and Date fields. Select those and any other desired field and continue clicking "Next".
4. In Filter tab, include Date to set the Date range, and click "Add New Filter" to select a second filter to include only the mailboxes that you want included in the report (such as Department).
5. Select the Group tab and include DisplayName so that you can calculate averages per mailbox.
6. Select the Format tab and click on Advanced Summary Calculations
7. Add a check mark in the Avg column for ever field you would like to average (Internal Messages, Internal Volume (KB), Total Messages, etc).
8. Clear the "Show detail records." checkbox.
9. Click OK to close Advanced Summary Calculations.
10. Complete processing the report.
The above should generate a table of daily averages per mailbox that are calculated over the specified time period.
