You may never say that everything in the Other page is spam, but if you present moving all messages not from friends into a folder called Other to solve the spa

You may never say that everything in the Other page is spam, but if you present moving all messages not from friends into a folder called Other to solve the spam problem... Either you're going to have a horrible false positive rate or a horrible false negative rate, because sender email address is a really poor feature to determine spam from ham.