I am trying to help someone break the habit of delaying too long in replying to emails. For a select group of email senders in Gmail, I'd like to set up some way of seeing how long it has been since the last received email that hasn't been replied to, and then sort that list by the longest period.
In essence, this is a per-person stopwatch counting how long it has been since email from that person was received. At the top of the list are the people that have been waiting longest for a reply (longest running stopwatch), and at the bottom those that have just recently sent email (shortest running stopwatch).
When I reply to someone they drop off the list until they in turn reply, at which point they come in at the bottom of the queue again (stopwatch resets).
Is there a way to configure a filter, mailbox view, or some other sort of report in Gmail (or some tool that plugs into Gmail/IMAP) that could show a view like this?