2-10-25 - Hello all on here -- I just called Apple about this mail problem that happened when my IPhone updated to the IOS 18.3. I got ahold of someone in Canada who helped me to fix this & want to let other know how to do it on here.
***Go to you Mail app & it will show you all of your "Mailboxes" such as (All, ICloud, Outlook, gmail, aol, etc. **What you have to do is go to all of them that you get your emails thru, then open for Example (ICloud) & then in the upper right hand corner there are (3) dots -- Open that up & Check "LIST" instead of Categories and it will fix that email you have chosen, then go to all of the other emails you may have listed & do the same thing & switch it back to "LIST" and it should fix all of them. **Also if you have an IPad with the Mail App Icon, do the same on there too.
This young man who helped me was located with Apple in Canada -- and he said this is a new feature for IOS 18.3, and you have to go in & change it back to LIST if this happens. **Also, he said to go to Apple.com for any updates on any new IOS Software updates or anything else with Apple. So I hope this helps everyone to fix this problem for our mail - PH