After a migration from Exchange 2003 to 2010, I have three users that continuously appear in the Microsoft Exchange Troubleshooting Assistant as "Active Users". As seen in the picture, the first user is reported to have a high usage due to MAPI SetColumns. The second is a high user because of MAPI FindRow. The third is reporting the MAPI WriteStream operation as being the reason. I'm not familiar with what these messages mean or how to fix them. I've read reports that these could be results of corrupt calendar items or messages hung in the outbox. None of the users seem to have anything in the outbox. The "recover deleted items" console is also very clean. I have done a mailbox repair request in 2010 for all three with no change in performance. Any ideas?