HowTo enable a "user not found" error-page after SSO-Logon

Hello experts,

I need some brainstorming and ideas, where to look for informations. Our SSO situation is the following:

We have a Login-Modul-Stack with

• SAML2LoginModule
• BasicPasswordLoginModule

When a user call our portal, he will be redirected to the SAML-Identity-Provider. This says "ok". Then the user will be redirected to the portal again.

Now I want to decide:

1. user has an account in the portal => open portal and enjoy
2. user has not an account in the portal => show html-page, which informs the user, that he has not access to the portal.

By now in the second case, the default login page with inputs for username and password are displayed. That we don't want anymore.

Is there a solution to configure the desired behavior?

Thanks for your comments.

Greetings,

Thomas