When a student is deleted from the Manage Students tab, Gradebook creates a backup of the student's data just in case this data is ever needed or if by chance the deletion was in error.

That is great, but is it possible the email to the teachers can help explain what is going on, rather than a confusing email?

Maybe the email needs something like: "We noticed a change in your rosters, so we are making a backup of your gradebook "

The current email report teachers receive is confusing and a large portion of our teachers are panicked that their account was compromised.