[Nextgrid]

A solution to avoid declaring bankruptcy would be to sort by sender. Turns out even in the fullest inboxes, the actual number of senders is manageable, and you can easily select all for a given sender and flag (for stuff that does require actioning), delete or archive.

Ideally, do this in conjunction with unsubscribing from the associated list and/or create rules so that automation takes care of future emails of that kind.

It might take you a few hours but in exchange you'll get back a usable inbox that will remain usable in the future thanks to the rules you set up.