Keep window/tab open on move or delete, but only sometimes...

I'm aware (e.g. https://support.mozilla.org/questions/1277401) of how to toggle whether the message window stays open (opening the next message) when an email is moved or deleted. But I would dearly love for it to happen only sometimes. Specifically, when a new message comes in, I want to read it, usually move or delete it, then read the next new message, if there is one. But if the next message is an old one, I don't want to keep having it shown to me. I keep my inbox fairly tidy, but I'm getting sick of seeing that message from a year ago that doesn't have a better place to be. So, after moving or deleting a message, if there is an '''adjacent''' unread message, keep the window open. Otherwise, close it. If there's an unread message somewhere else in the folder, don't jump to that one. Trust that I've left it unread for a good reason, and don't want to now constantly get shown it, and also have to remember to mark is as unread again. If it's easier to look for other unread emails based on dates, a few days (enough to span a long weekend, for example) would probably be enough, a week at the most. Or make that number user-configurable.