If we choose Email Address, what will happen if a user does not have one in the IAM Service?

Since the Alias ID is an additional way to login to the NCEdCloud, if a user's email address is not present they can still login using their UID.

Please see the following FAQ for further information about getting email addresses into the NCEdCloud IAM Service: https://ncedcloud-dev.mcnc.org/content/why-employees-email-wrong-or-missing-ncedcloud-iam-service