@GossiTheDog Very sad. I used Opera in the v7 through v10 days, I guess. It has an integrated email client, and that email client had some extremely clever and useful organizational features that I've never found a good substitute for.

Basically, it offered a tagging system for incoming email, but it could tag new mail automatically, and crucially, it would learn and improve from user actions and corrections. I don't know how it worked but it did work, and it was amazing.