A number of Gmail settings are the kinds of things you can set and forget -- like mail forwarding and delegation.
It can be pretty easy to forget about all the settings we have enabled years earlier. "So, for about the next week, if you use Gmail's forwarding or delegation features you will see a message at the top of your inbox each time you sign in. The notice asks you to review your settings and confirm they are still what you want," informs a team member of Gmail.
"If things look right, you are good to go. The message will stop appearing in about a week. If you see any unfamiliar accounts or forwarding setups you no longer need, review your settings and change them as appropriate," added the team member.
Note that any unfamiliar accounts may indicate that your password has been compromised and you should change it immediately.
[Source: Gmail blog]