Think about what actually makes an inbox oppressive. It is rarely the writing most replies take ninety seconds once you have decided what to say. It is the not knowing: forty-seven unread, somewhere in there three things that matter, and no way to find out which without reading all forty-seven.
That is a sorting problem, and sorting is exactly what an agent is for. Pattern-matching across many short messages is also where the current model is strongest its tool-use scores went up in the last release even as its long-document accuracy went down.
The exhausting part of email is triage, not composition. Hand over the triage and the composition stops feeling like a burden, because you are only writing the three that mattered.
The second problem is different in kind. Deciding what you owe someone whether this needs a reply at all, whether it needs a warm one or a brief one, whether the honest answer is no is judgement about a relationship. An agent that offers to do it is offering to guess, and it will guess plausibly, which is worse than guessing badly.
So the workflow below is built around a single division: the agent produces lists; you make decisions. Every pass hands you an artefact to act on rather than an action already taken. That is not timidity it is the arrangement that actually saves time, because the reviewing is fast and the undoing is not.