Starting two days ago, users started complaining that their SEND items failed to show in SENT folder. One complained that she gets "The operation failed" a lot in her OUTLOOK so she closes and re-opens Outlook several times a day.
I ignored it for a day and then it started happening to me too. Sometimes INBOX failed to show all the items. When I tried to move the mail item to a folder, it fails too.
So it is consistent with what has been happening to other users on the same network.
Where should I begin to troubleshoot this type of problem?