The trick, somehow, is to not do that. (The word is “dweebling” apparently.)
The trick is to know that email is vitally important and treat that response like it is one of most important things you’ll do that day. (Not that Paul doesn’t already know this, I’m just talkin’)
The trick might be to shoot them a one-liner back even though it is less than it deserves, if that’ll help your brain to more later. Or maybe you need to trick your brain into it with something simple like “mark as unread” or snoozing it.
The trick might be adjusting your brain. If you never replied… was it actually that important?