Instead of deleting the entire mailbox where someone loses all their life's worth of emails, can the mailbox be compressed and stored. If space is the the only issue for which the mailbox is deleted after the account is inactive for 12 months. Maybe keep the compressed data for another 2-3 years in case it needs to be recovered. 12 months inactivity is too short of a duration to delete the entire mailbox. Also some advance notice to the phone number and the alternate email address on the account would be helpful.