Problem
You've received a message from Microsoft with subject: "Your OneDrive is about to be deleted", and the body includes: "personal account has been unused for two years" and a Note: "Applies only to your personal OneDrive account".
When an MSU user receives such a notification it may be misunderstood as possibly pertaining to their Spartan Drive access.
Environment
Microsoft OneDrive
Spartan Drive
Resolution
The notice is actually a legitimate notification about a PERSONAL OneDrive account signed up for with your @msu.edu email address that has perhaps been forgotten and has nothing to do with your MSU-related OneDrive account.
Microsoft provides more information about the notification (link).
Recipients can feel free to navigate directly to https://OneDrive.com (link) (best to use a different browser than you use for business purposes) and log in and assess the personal account and content saved there.
Cause
See above.