How to ‘Star’ and ‘Unstar’ Gmail Messages
There are two ways to put a star next to one of your emails:
Select the small star outline to the far left of the message when you’re viewing the list of emails. If the email is open, go to the More menu and choose Add star. Or, select the star outline on the far right side of the top of the message (next to the date and time).
You can also star messages before you send them by adding a label to the outgoing email through the More options menu on the bottom of the New Message window, via the Label > Add star option.
Remove a Star From an Email
To remove a star, just click or tap it once more. Each selection will toggle between having a star and not having one. However, if you have more than one star configured (see below), you can keep clicking/tapping to cycle through the other stars you have set up. Just stop on the star you want to use. Or, if you decide not to use a star at all, just keep cycling through them until you reach the option without a star.
How to Use Custom Stars in Gmail
The other, non-yellow stars, supported by Gmail are accessible through the settings:
