Changing default paragraph line spacing from auto to 0

How do I set the default paragraph line spacing from auto to 0 when a new
mail message is being created? I am currently using Word 2003 as my default
email editor. I am currerntly selection all the text above the signature,
going to the menu and changing the paragraph before and after spacing from
auto to 0. However, this is getting old. I have to do this every time I
open a new mail message. I have tried changing the Normal.dot, Mail.dot, and
tried changing styles without any luck. Please help.