The super-trustworthy, anti-phishing key for Gmail Inbox

Gmail labs has introduced a new security feature by which Authentic emails can be verified easily. It will display a security key at the top of the mail if verified. You can enable this feature by enabling "Authentication icon for verified senders" from the Labs tab under Settings.

It's a bit of work for senders to make their email super-trustworthy, which is why this feature is limited to just eBay and PayPal right now. More services will be added to this list which Google will notify as it is done.

Official Gmail Blog: New in Labs: The super-trustworthy, anti-phishing key