Settings > Message Highlighting
 
You can set up rules to highlight specific messages. You define rules based on one of the fields in an email message (From, To, CC, To or From, To or CC, or Subject) and a value that you specify. Messages that match the rule are highlighted by a color that you selected. For example, you can add a rule to highlight, in green, all messages that contain "info" in the "From" field.

For message rules that apply to highlighting multiple messages, the first rule that applies to the message overrides subsequent rules. You can rearrange the order in which rules are applied.
Priority Color Rule Actions
There are no highlighting rules to display.
  Preview   

Select the message you want to view.