Then write mail rules. It's really easy and personally I couldn't survive at work without them. That's a big part of why it's nice: You can choose how it works unlike practically everything else these days.
That ties the app to be usable only with network access (which is fine for, e.g., Youtube, but not for all apps!), and also includes a highly variable lag.
>But I don't want so many mails in my inbox
Then write mail rules. It's really easy and personally I couldn't survive at work without them. That's a big part of why it's nice: You can choose how it works unlike practically everything else these days.