So this request is a little out there, but leaving it here anyway.
I would love the option to sort emails from Oldest to Newest. Not all the time, but as an option. When emails are ordered new to old, i end up reacting the the newest emails and ignoring the oldest.
I would like to start attending to emails in a less-reactionary, First-In-First out process.
Another idea would be to allow the inbox to be filter by date. Essentially, filter out any emails that were received same-day and only show emails that are at least 1 day old. This is taken from Tony Hsieh's "Yesterbox" process: https://yesterbox.com/