It is my opinion that POP email is less reliable than IMAP/iCloud. Apple expects mail to be IMAP and this gets the most validation and testing. POP is like a legacy. Same with “on-my-mac” mailboxes. Last time I did a migration to a new machine, my on-my-mac mailboxes were not migrated. I also had problems with my on-my-mac mailboxes in the past. I had to restore from backups.
There is an understandable logic to believing that local Mail will be more reliable than anything on a “cloud” where it could be maltreated by a third party…but this has not been my experience.
If you have more than a single device having mail in sync across them all is a great benefit.
As I said …all IMHO.
After taking some time off to de-stress, I’m back at the computer. Sonoma offered me a firmware update to my Studio Display and I accepted. Only AFTER downloading the firmware update, did I discover that it was necessary to restart the computer, not just the monitor.
After jumping through those hoops, I now find that Mail works properly. It appears that restarting the computer has mysteriously solved all my problems.
I had restarted Mail multiple time attempting to solve the problem not no effect. I had rebuilt the Spotlight index how to solve the issue of being unable to search for emails in Mail (I hadn’t brought this up not wanting to confuse the issue).
So, it appears the old adage of “unplug it, count to 10 then plug it back in” still holds.
Thanks for all the help, I really appreciate it.
On Windows, when I had to use it at work, we used Cntl-Alt-Del as a panacea for problems.
More recently, rebooting macOS is becoming an effective procedure to address mysterious problems.
If the solution is not quickly apparent, try to reboot!
To be clear, there’s nothing new here. It has always been worth restarting a Mac when there’s something that doesn’t respond to other troubleshooting steps.
This reminds me of problems I have had in the past with Apple Mail: especially if you are using POP3, it can take an inordinately long time for Apple Mail to find and reorganize all your email after a major OS upgrade. Changing to IMAP made a big improvement. The best thing in my experience is to leave it several hours or overnight before you restart it, although you still may need to restart it once it’s finished.