[[ "MDN/send", {
  "accountId": "ue150411c",
  "identityId": "I64588216",
  "send": {
    "k1546": {
      "forEmailId": "Md45b47b4877521042cec0938",
      "subject": "Read receipt for: World domination",
      "textBody": "This receipt shows that the email has been 
          displayed on your recipient's computer.  There is no 
          guarantee it has been read or understood.",
      "reportingUA": "joes-pc.cs.example.com; Foomail 97.1",
      "disposition": {
        "actionMode": "manual-action",
        "sendingMode": "mdn-sent-manually",
        "type": "displayed"
      },
      "extension": {
        "EXTENSION-EXAMPLE": "example.com"
      }
    }
  },
  "onSuccessUpdateEmail": {
    "#k1546": {
      "keywords/$mdnsent": true
    }
  }
}, "0" ]]