Email messages in your profile can be starred so you can highlight them as important to yourself and others who log in to the profile.
Head to Messages > Emails to see your email messages.
A message that has not been starred with be displayed with an empty, outline star.
Click the star to star the message. It will now show as a filled star and the star status will be visible to all logins on the profile.
If you want to see only starred messages, you can use the checkbox to filter the messages displayed. You can search for a particular message by name with the starred filter applied.