Re: Mail won't open in 2021 Macbook Air Sequoia
After trying to open Mail: (ie: when "with the black dot underneath it")
Wondering if you have tried clicking File > New Viewer Window to see if Mail opens a window
Else: If you haven't already tried this sequence:
Try clicking the Apple menu (black apple: on the left in top menu bar), and choose "Force Quit"
From the small menu that opens: Click on "Mail" from the list of open apps to Force Quit Mail
Then choose Apple menu > Restart to restart your Mac: wait while Mac restarts, and log-in again
(Deletes temporary files, re-establishes connections, may update recent setting
changes etc, and often restores order if something is not working as expected
Now open the Mail app, and see whether it is working ok
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More trouble=shooting articles online (from Apple Support) if needed:
See what to do: If an app on your Mac stops responding, quits unexpectedly, or won’t open - Apple Support
and
If you can’t send or receive email on Mac - Apple Support