I'm unable find the "Copy formatting" button under Outlook 2003 Professional?
In fact it is the integration of Word 2003 in Outlook 2003 that allows you to use this option.
1) Tools / Options / Mail Format tab,
2) Check the 2 boxes: Use Word 2003 to edit and read email messages
3) Create a new message, right-click the toolbar and select "Customize"
4) Select the Commands tab
5) Choose Format
6) In the right pane scroll down to "Format Painter"(the little brush ...)
7) Drag the icon to the tool bar
Thanks to Vulcan for this tip!