Below are the two methods that helped me figure out the problem that kept Outlook consuming memory. Office Addin Manager Power Explorer Check one after the other to find out what worked for you. In ...

Outlook add-ins or other programs could be preventing Outlook from closing properly. While manually ending Microsoft Outlook's process -- Outlook.exe -- using the Windows Task Manager can help close ...

For how long? Outlook does some housekeeping the the PST/OST file on your computer after you close the client itself. I've seen this take more than a minute in certain rare cases.