Email Enhancements for API

There seem to be limitations to the quantity of API calls I can make. One of the problems with integrating with other platforms is linking to a user account. The easiest way would be email, but the API supports only the username header. I would like to see a Api-email to be able to pass a post as the user (for example).

Additionally, the query to get all users does not provide the primary email, so I have to then loop through each user to get their email (and then exceed my API call thresholds). So linking an email to the user is not straight forward as well.