- If running, close the Apple Mail app.
- Open a new Finder window. (Finder > File > New Finder Window)
- To view hidden files, use <cmd><shift><period>. When done with these steps, just use this key combination to get out of "hidden" view.
- Select your Time Machine backup drive from Finder.
- Open: Backups.backupdb > Your Mac's Name > The backup folder with the date you want to restore from > Macintosh HD - Data > Users > Your User Name > Library > Mail > V10
- Copy (NOT move) the entire V10 folder somewhere on your Mac, preferably somewhere not syncing with a cloud service, for example Downloads.
- Open the V10 folder you just copied to the Downloads folder. You’ll see a bunch of alphanumeric folders ... one for each email account and for "On My Mac." Open each one until you find the mailboxes in the account you’re looking for. Note where you located it.
- Open the Mail app.
- Choose File > Import Mailboxes, navigate to that location. In the example, Downloads > V10 > Alphanumeric folder > the appropriate On My Mac mailbox.
- Choose “Import as Apple Mail”.
- Next, in the Mail app, you’ll see a new “Import” folder, maybe with another sub folder. Your mail should be in there.
