• Open Outlook Express
• See where it says From and Subject and Received? Well RIGHT click anywhere in that thin area and then left click on Columns
• You should now have a little window on your screen with the names of the columns that are available. You might need to scroll down to see them all but in there is Size. If you left click the little box in front of Size it will place a check mark there

• Click OK

Now you will have that column visible so that you can see the size of incoming emails. You can change the width of the columns so that it all fits on your screen how you like it. To do that hover over the dividing lines between From, Subject or Size until your cursor changes to a + looking thing with arrows then left click and drag the column how you want it.