The below report show different Total number of message for user nasser the report generated by  "number of message by sender".

Sendded Scheduled report show Total number of  message for user nasser =47085  (picture 1)

Report from manageengine tools show Total number of sent message for user nasser =76853  (picture 2)

Scheduled Sent Report to email  Report name ("number of message by sender")

Report from Manage Engine Tools Report name ("number of message by sender")

 Best Regards,