Gmail team has release another new feature called “Arrow indicators.” Once you enable, "personal level indicators" put arrows next to messages in your inbox so you can tell if an email was addressed to you, a group, or a mailing list that you're on.

A single arrow ("›") is automatically placed next to emails sent to you and others, and double arrows ("»") next to emails that are sent just to you.

I personally get a ton of email from lists (mostly from my college days when I subscribed to student group lists after a campus activity fair), so it's helpful to see my inbox annotated with arrows that tell me which emails are likely to warrant replies. If I get a bunch of emails with no arrows at all, I know they are probably from mailing lists. Give it a try for yourself by switching the "Personal level indicators" option to "Show indicators" under Settings.

Google, Gmail, New Features