Moving to your inbox, the selection criterion you should use is one simple question: does it spark joy? The goal of the KonMari method is to choose what you want to keep, not what you want to get rid of. For example, my coworker keeps the emails with company morning news because she likes them, aka they spark joy. I, on the other hand, get what I need from them and move them to trash to make room in my inbox.
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