How can you set Outlook to show all my mail as a plain list without this grouping?
This view setting can be changed in the following way;
* click on the “tab View” option, Then expand the Arrangement box via the Expand Ribbon Gallery button
* Now you can disable: Show in Groups
Disable it via View Settings dialog
An alternative way to disable this option is via the View Settings dialog
* Click on “Tab” View then select the button View Settings
* Now select the option “Other Settings” and then disable the option: Show items in Groups