[[ "MDN/send", {
  "accountId": "ue150411c",
  "sent": {
    "k1546": {
      "finalRecipient": "rfc822; john@example.com",
      "originalMessageId": "<199509192301.23456@example.org>"
    }
  }
}, "0" ],
[ "Email/set", {
  "accountId": "ue150411c",
  "oldState": "23",
  "newState": "42",
  "updated": {
    "Md45b47b4877521042cec0938": {}
  }
}, "0" ]]