Thank you Apple!
Finally, you've taken care of cleaning up my graveyard of 20 years worth of mails, leaving only the tombstones (headers) of mails, but letting the bodies rot for good.
I was always feeling bad about those several 100k dead (mail) bodies that were lying around, now you've put them to rest in peace.
Thank you.
Next time, could you please be so kind as to consider doing that with my Photos? I really start feeling old looking at me when I was so much younger.
Just remove them.
PS For the necrophiles in this forum, a backup of Mails using Carbon Copy Cloner, and then one-by-one restore of the subfolders of ~/Library/Mail from the backup using Apple Mail's import function, appears to resurrect the mails consistently, including their folder structure. Since resurrection processes historically tend to take three days, I am not concerned that this one is hanging around since a night.
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The Mail problems have not been fixed.
Yes, they are fixed. Also, that fix freed up considerable disk space. Win-Win!