We have written a custom claims provider for ADFS. It's all working fine: you enter your username and credentials in our login page, and it authenticates you to ADFS. There's just one annoying omission: if you come from Office 365 portal and enter your email address, you get redirected to ADFS, then to our login page... but without the email address. You have to re-enter it before you can login.
I can't see anyway to request that ADFS forwards the email address as part of the SAML request, or to check if there is already an email address associated with the SAML request.
Regards Robin Withey