Default fonts can be changed in the Outlook Options pane. To change the default font, follow the steps below:

1. Open Outlook .
2. Select File in the Outlook toolbar.
   
3. Select Options.
    
4. Click the Mail button to edit the mail preferences. Then click on Stationary and Fonts. 
   
5. Note that you have to change the default settings for New mail, Reply or forward and Plain Text messages.
   
6. Select Georgia Font, with an Automatic Colour and Size 12 font. Press OK to save these changes.