Because so much spam and phishing email comes from entities pretending to be either eBay or PayPal, Google thought it was worth protecting Gmail users from attacks. The latest Gmail Labs tool will make absolutely certain that any emails that hit your inbox from eBay and PayPal are actually from eBay and PayPal.The new Lab is called "Authentication icon for verified senders." Essentially, Gmail is requiring that any email coming from eBay or PayPal has to originate from their respective domains. If the email addresses don't end in "@ebay.com" or "@paypal.com", then Gmail completely rejects the email.

Google says it is actually pretty difficult to do this, which is why the feature is limited to just eBay and PayPal to start. Google noted that it will continue to add more financial institution senders to the verified list over time.

With the lab enabled, you'll know for certain that any email from eBay and PayPal is authentic, and Gmail will display a little "key" icon next to the email. This means the email is "super-trustworthy".

Not clear on what super-trustworthy is? Brad Taylor, Gmail Spam Czar, explains: "'Super-trustworthy' is a technical term I just invented that means: (1) the sender, usually a financial institution, is a target of phishers, (2) all of the sender's email is authenticated with DKIM, and (3) Gmail rejects any fake messages that claim to come from this sender, but actually don't."

If you're a heavy user of either eBay or PayPal -- and you use Gmail -- it is probably a good idea to enable this particular Gmail Lab, as it could prevent you from becoming the victim of a phishing scam.