Most people in the workforce send and receive email.
And most of the places I've worked we use Microsoft Outlook.
And I used to spend enormous amount of time organizing the folder structure.
First I'd have a folder for everyone who sent me email.
Then I'd have a folder for every project / application.
Except sometimes they would overlap.
And it actually caused more confusion.
So lately I've condensed everything down.
To a single Outlook folder.
And every email goes in there.
And if I need to search for an email, I simply search for the topic in all folders.
Typically find the email with little effort.
And that has actually saved time and reduced clutter.
Some people get hundreds or thousands of emails per day.
I only keep outstanding email in my inbox.
If the email has been completed or no longer needs my attention, it goes in the single folder.
And that's how I do it!