You can automatically force emails to change font and colour based on key words within the subject or body of an email.
1. Within Outlook, click on the View tab and then View Settings
2. Click on Conditional Formatting...
3. Click on Add and give the new rule a name
4. If you want to change the Font/Colour these messages will appear in, click the Font... button and make your selection
5. Click Condition... and where is says Search for the word(s) type in your key words, you can have multiple, if separated by a comma
6. Click OK three times