Related Questions:
How do I change the font size of my emails?
Can I adjust the font in my email templates?
Answer:
You can change the font and style settings of your Email Templates from your Settings.
Go to Settings
Click on Templates & Files
Click on Email Templates
Hover over the template you want to edit and click edit (pencil icon)
Use the various options in the text editor box to make your changes
Click Save
You can also change the default style settings for all composed emails. Changing these settings will not affect existing Email Templates.