1. Check if you are in the html format mode – this will allow you to use your own information and font.

2. Make sure your fonts have been set in Outlook so they apply to new emails, replies, and incoming emails.

3. Check if you have created any Outlook rules for the font settings.

4. See if the compose settings have been changed such as when you changed the font size or style.

5. Ensure that the font is still supported in the latest version of Outlook since some older fonts are no longer available.

6. Check any HTML or Rich Text Formatting data which may be overriding the font settings.