Some time ago I imported all of my email database into DTPO and deleted my actual Mail database, thinking that I had a backup on my external drive. I probably have it in one of my Time Machine backups (?). Is there a way of exporting all my email out of DTPO and importing it back into Apple Mail?
You could try File > Export > As Unix mailbox…, and then in Mail use File > Import Mailboxes…
I’d experiment with a small selection of mail first just to check whether the process works as expected. I’d be doubtful that conversations will export/import with threading intact.
Thank you. Works great.