SAML applications claim mappings have email address mapped. The User Principal name (UPN) of the users are not changing however the email address are changing in Active Directory. Claims are created every time you log in with your UPN. Then CAM checks the email address associated with the UPN. As a result, if the email address is changed the new email address will be sent to the backend application. So as long as the backend application recognizes the new email address it will work.