A User is a member of your Mercura organisation (a Sachbearbeiter) — the person who works a request and is named as its responsible user. This is distinct from the business-partner resources (customers / suppliers / contacts); a User logs in to Mercura, a Contact does not.

The resource is read-only. Users are managed in the Mercura admin UI; there is no public write path.

You can:

• GET /users?email=<addr> — look a user up by email (case-insensitive, exact match). email is required. Returns a paginated envelope with the matching user, or an empty data array when the email is unknown in your organisation (never a 404 — the status code does not reveal which emails exist). next_cursor is always null — every match fits in one page. Almost always a single match; email is not guaranteed unique, so if more than one user in your organisation shares an email, all are returned and you disambiguate by id.
• GET /users/{user_id} — fetch one user by their Mercura user id (the id field from a GET /users response).