An enterprise computing environment such as a corporate web portal includes an intermediary server, a sign on service, and one or more backend enterprise systems managed by resource managers. Before or after user primary logon, which establishes a user primary account identity, the intermediary server uses its own identity to authenticate to the sign on service its right to retrieve user secondary account identities with respect to the backend enterprise systems. Retrieved secondary account identities are then used by the intermediary server to perform user secondary logons to respective resource managers in the environment. The intermediary server also manages the passing of resource requests and associated replies between the user and the resource managers.