I hope it works for you if you have the same problem I did.
If you created a bogus account in step 1, be sure to delete it or Mail will get stuck on trying to get it to work.
You should finally get the full Cannot Verify Server Identity dialog with Continue, Details, and Cancel. Tap on it to get the details, and hit Delete Server. by Bryan Vitale on 10 October, 2022 A couple of years ago, I serendipitously ran into Bug Fables, a love letter to the Paper Mario series that exceeded all of my expectations. Just get it to be saved as a legit-looking account, and you should be OK.
Only applicable if you have one mail account on your phone: Create a bogus mail account with fake settings.If you have more than one mail account, skip to step 2. Someone else mentioned a version of this solution earlier, but here's a step-by-step guide to how I finally cleared it up after a day of dangerously high blood pressure: If you're able to receive but not send mail, I can confirm that this is all related to a bug in the SMTP server settings stored on the device.