const options = {method: 'GET', headers: {'X-API-Key': '<api-key>'}};

fetch('https://api.mailchannels.net/inbound/v1/domains/{domain}/downstream-address', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.mailchannels.net/inbound/v1/domains/{domain}/downstream-address"

headers = {"X-API-Key": "<api-key>"}

response = requests.get(url, headers=headers)

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.mailchannels.net/inbound/v1/domains/{domain}/downstream-address",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "X-API-Key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

curl --request GET \
  --url https://api.mailchannels.net/inbound/v1/domains/{domain}/downstream-address \
  --header 'X-API-Key: <api-key>'

{
  "records": [
    {
      "priority": 1,
      "weight": 1,
      "port": 1,
      "target": "<string>"
    }
  ]
}

{
  "errors": [
    "<string>"
  ],
  "code": 123,
  "message": "<string>"
}

{
  "errors": [
    "<string>"
  ],
  "code": 123,
  "message": "<string>"
}

{
  "errors": [
    "<string>"
  ],
  "code": 123,
  "message": "<string>"
}

{
  "errors": [
    "<string>"
  ],
  "code": 123,
  "message": "<string>"
}