Currently, undergraduate students keep their University email for two semesters (excluding summer) after they are last enrolled. For instance, if your last enrolled semester was Fall 2019 then your email would remain active through the Fall of 2020. After this time your account will be deleted and will not be recoverable.
Graduate students keep their University email for three semesters (excluding summer) after they are last enrolled. For instance, if your last enrolled semester was Fall 2019 then your email would remain active through the Spring of 2021. After this your email will be deleted and will not be recoverable.
After you leave the University, setup a personal email account, update your email address on any online accounts, and notify contacts.