SSO with multiple Google domains

[Peter Schober]

* Knape, Dean M. <knape at njit.edu> [2017-11-02 16:18]:
> Google is suggesting using the relay state of the authentication request to
> derive domain information which can then be used to build the appropriate
> email address for the SAML response.  Is this something that can be done in
> the IdP?

Did you search the archives? That all sounds very familiar.
-peter