curl -X GET 'https://api.nuntly.com/messages/imsg_01kabn43yqyxn2bx4ve84mczd3' \
  -H 'Authorization: Bearer apk_xxx'

{
  "data": {
    "id": "<string>",
    "createdAt": "<string>",
    "inboxId": "<string>",
    "threadId": "<string>",
    "messageId": "<string>",
    "from": "<string>",
    "to": [
      "<string>"
    ],
    "cc": "carlo43@gmail.com",
    "bcc": "archive@company.com",
    "replyTo": "support@company.com",
    "subject": "<string>",
    "receivedAt": "<string>",
    "labels": [
      "<string>"
    ],
    "attachmentCount": 123,
    "headers": {}
  }
}