What is the reason I cannot receive email send to @ust.hk after gradudated?

A student network account will be terminated when the student leaves the University.  Upon successful completion of study, a grace period of four months will be granted. After the four months grace period, your @ust.hk/@stu.ust.hk email address will be deleted and you can no longer receive email addressed to your @ust.hk/@stu.ust.hk email address.

Students should use your @connect.ust.hk email address to communicate with HKUST users and outsiders once you have switched to @Connect as your @Connect account will not be expired.