Most alumni do not want a second mailbox to check. They have one. It is the personal Gmail or iCloud account they have used for a decade, or it is the work mailbox at the employer they spent the last five years at. What they want from the institution is the address, not the storage.
Forwarding fits that shape exactly. Mail addressed to name@yourdomain.edu lands in the alum's existing personal mailbox. The institution never has to license, store, or troubleshoot a separate alumni mailbox. The alum never has to decide whether the .edu address is worth checking. The promise on graduation day is honored, and the operational footprint stays small enough to justify in any budget cycle.
Alumni Forwarding is part of the broader Route group, the products that handle mail movement across migrations, outages, and lifetime address commitments. It is the version of forwarding scaled for institutional populations rather than individual domains.