Below are some suggested actions to resolve this issue:

1. Check the current version of Outlook installed in your device.
2. Update your Outlook and other Office applications to the latest version.
3. Check your email settings and adjust the font, font size, and font style accordingly.
4. Verify if theme settings might be interfering with the font settings.
5. Uninstall any add-in, tools, or plugins that might be causing an issue with the Outlook font settings.