Why does the Mailbox Activity Summary report display graphs only for the Top 10 users?
The number of records displayed in a top-N type graph is specified in the Select Top text box. The text box can be left empty to get the all of the available records. A graph usually has a maximum number of records it will display. This avoids render time-out issues.
The Mailbox Activity Summary report does not include a Select Top control. It's graphs are hard-coded to cap at ten records.
Enhancement request TF00095115 has been submitted to Development for consideration in a future release of Messagestats.