If you want to change the default font in Outlook, do the following
Click on File in Outlook.
Click on Options.
Click on Email and then go to Stationery and Fonts….
You now have the possibility to define fonts for newly composed and replied messages.
Click at the respective type on Font…
Now you have the possibility to choose a font, a font size and the font color. Click on the desired option in the respective selection menu.
Then click on OK.
Click OK.
Click OK again to complete the configuration.
