I'm sure I'm not alone when I say that I have way too many email accounts to keep up with. I think I have around 8-9 Gmail accounts alone...how the heck do you stay on top of all of that? I have tried all of the tricks including mapping them to Outlook, the Gmail app on my phone...all with sub-par results.
I recently came across a product called "Shift" which has quite literally changed my life for the better. Shift is an app that manages all of your gmail accounts as well as apps like Slack, Trello, Youtube, and so much more. What I love about Shift is that in a single window I can see all of my gmail accounts plus my most commonly used apps. Shift also supports searching across all of your email accounts. No more trying to remember what email you used for that thing you're looking for (we've all been there). Finally you can fully customize how Shift works so that you can become extremely productive using whatever workflow you want.
I'd urge you to try out Shift if you are like me and like some order in your life. You can try it for free (with one email account) to see if you like it. To truly unleash it's potential it does cost $99/year but I think I've already made that back in time and avoided headaches.
Try Shift HERE