I use Mailstrom. It allows you to delete emails in batches based on different groupings (sender, subject, shopping, time, size etc.) and also unsubscribe. When my mail is getting out of control I go in and delete a couple hundred in a few minutes. It’s actually quite satisfying.
Edited: To add the link https://mailstrom.co/ (non affiliate). They have a free trial.
I use sanebox.com to auto-sort my mail. Yes, it's expensive, but it works really well. 3ish folders. News: newsletters that I may never read. Bulk: Receipts, etc. Later: Stuff I need to review at least every other day.
Then I also use https://mailstrom.co/ and Chuck (for iOS only) to do cleanups.
You can do it. Three months ago, i had 22k mails.
I kept trying to delete stuff using gmail alone. Went down to 17k. But it was too difficult.
Then, i paid for one month account for mailstorm. Connected my gmail to it. Went from 17k to 2k with it. It was super easy as the app bunches all the mails from similar domains, people and so on.
Then switched to gmail for the last 2k as these were individual mails. So bunching just wouldn't happen.
Ofcourse i didn't delete every mail. Else, just select all and delete would have sufficed. I created multiple labels for personal/ and professional/. Gave appropriate labels to mails. Then archived them.
Then, i removed the promotions, updates, forums and social tabs in gmail. Made it all into one inbox.
Finally, using multiple inboxes feature of gmail, i have now 4 inboxes. #1 is the regular inbox, #2 is mails with label as defer, #3 is mails with label as waiting for and #4 is mails with label as someday/maybe.
Inbox zero wasn't an action. It was a project which spanned over 2 months. It seemee impossible and pointless to even bother with. I was able to do it. You can do it too!!
Now, i never wonder if i have ever missed anything to capture from my mails ever! Ping me of you have any questions about this!
Your email inbox is a terrible tool for storing knowledge, stop using it that way.
Use https://mailstrom.co/ to clear out the crud, then give inbox zero a whirl.
This is a good guide for implementing inbox zero: https://praxis.fortelabs.co/one-touch-to-inbox-zero-a74cfa02e5bf/