Hi,
If you are asking about New Outlook, in the New Outlook for Windows, the ability to customize columns in the message list view is currently limited or unavailable. If this feature is critical, it is recommended to switch back to the Classic Outlook by toggling off the "New Outlook" option.
For Office 2024:
- You can manually drag the border between column headings to adjust the width as desired(the arrow changes when it is in the dragging mode).
- To display additional columns, go to the View tab and select View Settings, then click Columns.
- In the Show Columns dialog box, select the desired column from the Available columns list and click Add.
I’m eager to hear back and work together to find a solution.