Open Outlook
Click **File**
Click **Options**
Click **Mail**
Click **Stationery and Fonts**
Under **New mail messages**, select the font and size you want
Under **Replying or forwarding messages**, select the font and size you want
Under **Composing and reading plain text messages**, select the font and size you want (if needed)
Click **OK**
Click **OK** again to close Outlook Options