curl --request GET \
  --url https://api.ahasend.com/v2/accounts/{account_id}/statistics/transactional/delivery-time \
  --header 'Authorization: Bearer <token>'

{
  "object": "list",
  "data": [
    {
      "time_bucket": "2023-11-07T05:31:56Z",
      "recipient_domain": "<string>",
      "avg_delivery_time": 123,
      "median_delivery_time": 123,
      "count": 123
    }
  ]
}