emails lost in accidental Inbox rebuild in Apple Mail

Hello all,

I accidentally rebuilt an inbox in Apple Mail; this inbox is for an old email account where the mails are no longer on the server, and thus the only copy of the messages was in Mail.

This appears to have deleted all the mails; following previous advice on this forum I have gone to ~/Library/Mail and hunted for the emails in the filesystem, yet I can't seem to find them (e.g. plaintext searches for names that should be there don't seem to reveal them). I have found the sent mail folder associated with this account; the corresponding "inbox" folder is empty, as in the filesystem as it is on Mail.

Previous advice on this forum led me to believe that these emails were only hidden and not deleted, does anybody know how to find them? (Or is it the case that new versions of MacOs actually delete them?)

Using MacOs High Sierra 10.13.3, Mail version 11.2.

Best wishes,

Nabil