MAU multi-tenant support

Feature: Provide a short title of your feature request/feedback.

Count unique email address across Auth0 tenants only once against MAU.

Description: Give us some details about your feedback/feature request. Examples, screenshots, videos, etc. are helpful.

Currently the same user, using the same email address, will be counted each time they are authenticated against a different Auth0 tenant. This goes against the spirit of counting unique users and artificially increases the MAU count. The technical solution to this problem seems simple and should be easy to implement as long as the email addresses associated with each tenant are retained during the overall MAU calculation.

Use-case: Tell us what you are building. How would the feedback/feature improve your experience?

We provide SaaS solutions for large enterprise customers. If a given customer purchases multiple products and each product uses a different Auth0 tenant the overall cost of IAM will increase for us and ultimately for our customers. Using multiple tenants in the overall design of the system should not be penalized by the MAU calculation.