I agree with you wholeheartedly re: processing your inbox as a specific task and not casually picking through it all the time, but I disagree about making multiple passes through it: picking off the easy ones, then flagging, then answering etc. Most people let the “difficult” ones fall back into the inbox — it’s too tempting not to decide how to handle them. They end up wasting time re-reading them again and again with each pass, and the inbox gets clogged up with them. IMHO once you pick up an email, you should never let it drop back in the inbox — you have to decide now what action to take (delete/archive/reply/action/etc.) and then get it out of sight and onto the relevant action list. It’s all too easy not to decide, and we have to lose this habit.