After a vacation, when I came back, my mailboxes had all disappeared. I had email, but the subfolders, which apple calls "new mailboxes", in which I had filed and arranged emails by topic, had all disappeared. Apple support had me do a restore from backup but this didn't fix it.
iMac
yep. it's empty. It says Maildata at the top, but the box is empty below
I already provided you with the solution (restore from Time Machine) , is there a reason you are not following that???
You were a great help. Finally got it fixed. After doing your steps, I then restarted iMac and then imported the mailbox folders.
Glad it's working now.
clicked "On My Mac" at the bottom of mailbox list and voila! All my boxes appeared. OS 10.12.6 iMac.
my mailboxes disappeared
