Gotcha. We definitely don't have fine granularity around when MFA is required (open issue here: https://github.com/FusionAuth/fusionauth-issues/issues/2285 ).

Other than that I'd suggest putting a page in front of our login pages with the domain logic, and modeling each set of emails as either an application, organization or tenant, depending on the specific features you need.

Either way, hope you find the right solution for your needs!