Flagging messages is a useful way to remind yourself to follow up on a particular message or mark a message so that it is easier to find in your inbox.
To flag a message, click the Flag button to the right of the message title in the View Pane.
To choose a flag of a different color, right-click the flag button and select a different color from the drop-down menu.
To mark a flag as complete, right-click the flag button and choose Flag Complete from the drop-down menu.
To clear the flag from a message, right click the flag button and choose Clear Flag.
Flagging messages is a useful way to remind yourself to follow up on a particular message or mark a message so that it is easier to find in your inbox.