curl --request GET \
  --url https://api-next.ofauth.com/v2/access/mass-messages/:massMessageId \
  --header 'apiKey: <api-key>' \
  --header 'x-connection-id: <api-key>'

{
  "id": 123,
  "text": "<string>",
  "fromUser": {
    "id": 123,
    "name": "<string>"
  },
  "media": [
    {
      "id": 123,
      "type": "photo",
      "convertedToVideo": true,
      "canView": true,
      "hasError": true,
      "createdAt": "<string>",
      "isReady": true,
      "releaseForms": [
        {
          "id": 123,
          "name": "<string>",
          "partnerSource": "<string>",
          "type": "<string>",
          "user": {
            "view": "<string>",
            "id": 123,
            "name": "<string>",
            "username": "<string>",
            "isVerified": true,
            "avatar": "<string>",
            "avatarThumbs": {
              "c50": "<string>",
              "c144": "<string>"
            },
            "ivStatus": "<string>",
            "isFromGuest": true
          }
        }
      ],
      "duration": 123,
      "hasCustomPreview": true,
      "videoSources": {
        "240": "<string>",
        "720": "<string>"
      },
      "files": {
        "full": {
          "url": "<string>",
          "sources": [
            {
              "url": "<string>",
              "width": 123,
              "height": 123,
              "type": "<string>"
            }
          ],
          "width": 123,
          "height": 123,
          "size": 123
        },
        "thumb": {
          "url": "<string>",
          "width": 123,
          "height": 123,
          "size": 123
        },
        "preview": {
          "url": "<string>",
          "options": [
            {
              "url": "<string>",
              "width": 123,
              "height": 123,
              "type": "<string>"
            }
          ],
          "width": 123,
          "height": 123,
          "size": 123
        },
        "squarePreview": {
          "url": "<string>",
          "width": 123,
          "height": 123,
          "size": 123
        }
      }
    }
  ],
  "previews": [
    123
  ],
  "isMediaReady": true,
  "mediaCount": 123,
  "lockedText": true,
  "responseType": "<string>",
  "giphyId": "<string>",
  "isFree": true,
  "isTip": true,
  "isReportedByMe": true,
  "isCouplePeopleMedia": true,
  "queueId": 123,
  "isMarkdownDisabled": true,
  "releaseForms": "<unknown>",
  "isFromQueue": true,
  "canUnsendQueue": true,
  "unsendSecondsQueue": 123,
  "isOpened": true,
  "isNew": true,
  "createdAt": "<string>",
  "changedAt": "<string>",
  "cancelSeconds": 123,
  "isLiked": true,
  "canPurchase": true,
  "canPurchaseReason": "<string>",
  "canReport": true,
  "canBePinned": true,
  "isPinned": true
}