Backing up the email database is probably a bad idea for an org like this, because they have data that isn’t allowed to be backed up.

I had a customer that got accidentally sent confidential data to the wrong email address and it was backed up for multiple months. In the end we left it in there but they considered deleting all the backups that contained this email.

That is a good reason for having short lived backups and an archiving solution with retention policies emails.