> Now multiply that interaction by 400 every week.
>
> Tell me how you would react then.
The only sane way: like a robot.
Please just stop caring and send 400 pre-canned, polite, terse and relevant answers per week. I am sure you are well able of automating your email software so the time required to select and send such a pre-canned answer becomes negligible compared to the time actually spent reading the corresponding submission. Bonus: you save time for the interesting submissions & discussions.
Real people have feelings. Silencing them when needed is part of being a professional.