Here's the quickest, easiest, and non-douchiest way to remind someone to respond to your email:

Send them back an email that says:

   bump.

That's it!  Just reply back to the email thread with the word "bump."

I learned this a while ago from my friend Sungho.  Leave it up to an Asian to come up with something so elegantly simple ;-)

The first time I ever saw this "bump" method in action was in 2011 when Sungho sent me a time-critical email......and I didn't respond:

A quick "bump" from him, and the burden once again fell onto me to respond.  AND he didn't sound annoying!

So next time you need a time-critical email answered, give it a bump!

Use this trick wisely my friend,

Neville Medhora

P.S. Share this trick with your co-workers:

https://copywritingcourse.com/how-to-remind-someone-through-email/

P.P.S. Check this out if you wanna see some other people's email open rates.