Students who are former SU employees and have their email routing to SU's Exchange service will not get set up automatically with a SUmail account. They need to contact the ITS Help Desk at help@syr.edu or (315) 443-2677 for assistance in getting transitioned from Exchange to SUmail.
Note that any migration of existing email messages in the Exchange system to the SUmail is at the discretion of the department that employed the individual and requires the department's approval.