put https://api.sandbox-v2.vault.ist/reg/user/email
This endpoint allows updating the user's primary email address.
No Confirmation Code: If no confirmation code is provided, a new confirmation code will be sent, and the response will return a 202 status code.
With Confirmation Code: If a confirmation code is provided, it will be validated, and the primary email will be updated. The response will return a 200 status code, and the old email will be marked as deleted.