This morning I am unable to retrieve mail from my ISP and I have an "Account Error" advisory at the top of my Apple Mail page - in a little black triangle. The Preferences show that iCloud is online but I cannot get it to go offline and allow my ISP mail to be online.
Every time I designate my ISP account as the online account, iCloud takes over and designates itself as online.
NOTE: My wife's ISP email, on the same machine but a different account, is just fine.
Update: I used Cocktail to rebuild the Launch Services Database, but that made no difference.
Update 2: And now, just as mysteriously as the problem arose, it has gone away. I went to fill my coffee mug and, when I returned, Mail had started working properly. Colour me confused, albeit relieved.
Edited by ryck (12/09/19 05:53 AM)
iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
OS Mojave 10.14.6
Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Time Machine on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro