List the contacts a campaign was sent to that never opened it. This is the v3 equivalent of the v1 campaign_report_unopen_list action.

Rows come back in the order the underlying query produces, so no orders parameter is accepted, and the response carries no meta.total: page until a short page comes back.

limit plus offset may not exceed 1000; a deeper window is a 422.

Requires the Campaigns feature and access to the campaign; a campaign the user cannot see is reported as 404 so the endpoint does not disclose which campaign ids exist.