eduPersonPrincipalName (eppn) is a user identifier attribute defined in the eduPerson→ LDAP object class. It is a scoped identifier for a person. As this identifier is often used by humans to identify the person it represents, ePPN values are often, but not required to be, human-friendly, and may change as a result of various business processes.
While an eppn's format appears similar to that of an email address, implementors MUST NOT assume that an eppn is a routable email address. If a service requires a user's email address, it MUST request it via a separate mail attribute.