Are you using Outlook stationary but are being driven absolutely mad because no matter what you try, you still get double spacing when typing in the email body. I’ve finally figured out a solution.
XP: C:\Documents and Settings\<username>\Application Data\Microsoft\Stationery
Find your stationary file (<stationaryfile>.htm) and then right click on it and choose edit.
In the styles section of the ribbon, right click on the “normal” style and choose modify.
Click on the reduce line spacing button, highlighted:
The select the new documents based on this template radio button and once you click OK and save, this should fix your problem!