API to retrieve users emails in case it is hidden from public

Currently it is not possible to retrieve email of user within the Org in case email visibility is set to "Only you and admins".

There are a couple of API endpoints, however, they are not working (expectedly) 

1. [{{{{{}baseUrl{}}}}}/rest/api/3/user?accountId=...] This doesn't work due to visibility of email
2. [{{{{{}baseUrl{}}}}}/rest/api/3/user/email?accountId=...]. This doesn't work because it's a user making the call not a whitelisted application.

There should be API to retrieve user email in case it is called with admin authentication (admin has permissions to view email).

Use case scenario: Implementation of user picker fields in JSM forms which should query list of users.