Problem with Entra ID SAML

Summary
SAML assertions don’t seem to work with mattermost vs Entra ID

I have set up my E20 Mattermost as a SAML app in Entra/AAD and I can seem to figure out what Mattermost will accept as SAML Claims.

For example:

AAD has http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress so I put emailaddress in the Email Attribute field.

The log says this:

SAML login was unsuccessful because one of the attributes is incorrect. Please contact your System Administrator., emailaddress attribute is missing

Yet, the Received Assertion info directly above this has this:
Error{{urn:oasis:names:tc:SAML:2.0:assertion Attribute} http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress [{{urn:oasis:names:tc:SAML:2.0:assertion AttributeValue} tom@xxxxxxxx.com}]}

I don’t know what to do about this.