My Font for Gmail™ is a Google Chorme extension. It changes the default font of Gmail to any font you like.
- Click the “wrench” icon on upper-right corner of Chrome,
- Select tools->Extensions->My Font for Gmail™->options.
- Choose a pre-defined font from the drop-down menu or enter any font in your system.
- Click “Save”.
- Refresh the Gmail page or re-open it.
Please note that this extension works best for plain-text emails. Rich-text(HTML) emails will possibly remain its original font because those emails can set their own font for each element. Usually this doesn’t bother me since they are already well-formatted.