Adding Fields to Your Folder Views
If you do not have enough default columns in your mail folders you may need to organise your e-mail by importance or size of your messages to find the large ones that are filling up your mailbox.
To add fields in the window
Right-click on the field headings.
Click on Field Chooser.
You will get a dialogue box where you can choose the fields you wish to add.
To add the fields, drag and drop the icons you want up to the column headings.
You can add as many fields as you like. However, keep in mind that, depending on the size of the monitor and the screen resolution you've selected, you will only realistically be able to have around 7-8 fields (depending on which ones they are) because they will not fit on the screen.
You will have to do this operation for all your folders and subfolders individually.