curl --request GET \
  --url https://api.terminal49.com/v2/email_submissions/{id} \
  --header 'Authorization: <api-key>'

{
  "data": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "type": "email_submission",
    "attributes": {
      "subject": "<string>",
      "body": "<string>",
      "from": [
        "<string>"
      ],
      "to": [
        "<string>"
      ],
      "cc": [
        "<string>"
      ],
      "sent_at": "2023-11-07T05:31:56Z",
      "message_id": "<string>",
      "in_reply_to": "<string>",
      "references": [
        "<string>"
      ],
      "content_type": "<string>",
      "documents_count": 123,
      "created_at": "2023-11-07T05:31:56Z",
      "updated_at": "2023-11-07T05:31:56Z"
    },
    "relationships": {
      "account": {
        "data": {
          "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
          "type": "account"
        }
      },
      "user": {
        "data": {
          "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
          "type": "user"
        }
      },
      "documents": {
        "data": [
          {
            "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
            "type": "document"
          }
        ]
      }
    },
    "links": {
      "self": "<string>"
    }
  },
  "included": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "type": "account",
      "attributes": {
        "company_name": "<string>"
      }
    }
  ],
  "links": {
    "self": "<string>"
  }
}