There is a new (yet hard-to-find) feature that enables you to set the color of your email messages to match the color of the applied tag. So, if you apply a yellow tag to a message, the message will be displayed in yellow in your inbox.
To enable this feature:
1. Click the Preferences tab, and select Mail. In the Displaying Messages area, select the Message Color option, as shown below.
Note: Don’t forget to click Save.
Before enabling Message Color, my inbox looked like this:
Now it looks like this, with the tag color applied to the entire message.