I don't use gmail but I have an email address from Microsoft (which is not m'y main one) : outlook.live.com does a good job filtering newsletters or promotionnal emails, or other terrible marketing practices, from individual ones, but it's not espacially performant when it comes to dealing with spam or scams. On this address I have a «please log in to your PayPal account for safety reasons blah blah blah» or «come buy our absolutely legal drugs to boost your performances» every three or four legit emails.