This is just a guess on part. Since they were dealing with confidential tax information, they probably aren't allowed to backup to local devices. Most of the work would likely have done on a secure file or database server. Generally speaking you don't want rank and file doing their own backups anyway..
I mentioned an IT person (they don’t follow normal IT protocol if a hard drive crash loses emails forever). What I don’t get is that email is only a small portion of the of a typical management job. There had to be word docs, spreadsheets, proposals, written policies, presentations, job reviews, resumes, etc.. etc... We are expected to believe that you lose a hard drive you lose everything?
If all her documentation was backed upped on a file server, so was her .pst file. No IT person is stupid enough to backup everything but email (even if this seems a little redundant if they were using a mail server). You can never have enough backup.
Now they claim at the time that emails were stored on a backup tape for three months. And that tape was destroyed. If this is true why didn’t they immediately recover her emails from backup when the hard drive was replaced? Why even attempt to recover the files off of the hard drive? They had an intact backup at the time the crash. Their explanation makes absolutely no sense.