mail won't launch after High Sierra upgrade
Since upgrading to High Sierra I've had really frustrating problems with Mail. I have several e-mail accounts: three g-mail, one Yahoo!, one iCloud, and one "other". These accounts work fine on my iPhone.
After upgrading to High Sierra on my 2016 MacBook Pro, Mail is unusable. When I click on its icon in the dock it starts, but it runs for only a second or two before quitting, with no error or other message--it just disappears.
I have tried deactivating all the mail accounts, in which case Mail seems to start and is stable. I have even deleted all the accounts and re-added them. At best Mail works for a while (like, several hours) but then resumes its unexpected quits.
What's the problem here? Do I have to downgrade to Sierra?
After two decades as an Apple customer, I have *never* had such a frustrating experience with Apple software. It makes me think that Apple is more a luxury accessories company than a computer and software company these days.
MacBook Pro (15-inch, Late 2016), macOS High Sierra (10.13.1)