How to map subject email address to request header name?

[Cantor, Scott]

> Re. scope of email address, I pay attention to the entity id of the IdP,
> which is meaningful to us.  But I will experiment with
> NameIDFromScopedAttributeDecoder to see what extra information that
> gives me.

True email addresses are not scoped, they're simply email addresses. It's not proper to apply scope filtering to them in general. If you want a scoped identifier, that's EPPN.

-- Scott