curl --request GET \
  --url https://api.utage-system.com/v1/accounts/{account_id}/scenarios/{scenario_id}/readers/{reader_id}/opens \
  --header 'Authorization: Bearer <token>'

{
  "data": [
    {
      "message_id": "<string>",
      "title": "<string>",
      "channel": "<string>",
      "subject": "<string>",
      "opened_at": "<string>"
    }
  ]
}