User emails are the email addresses attached to a Greenhouse user. A user can hold multiple addresses — typically one work email plus aliases or historical addresses — but only one is the primary, which Greenhouse uses for sign-in and notifications and is exposed as primary_email on the /v3/users resource. Use this endpoint to resolve a list of addresses back to users (e.g. matching candidate-attributed emails to interviewer calendars), or to audit which secondary aliases are verified. The primary email itself cannot be switched through Harvest; use POST /v3/user_emails to add secondaries.