gas_createDraftJP.js

function createHTMLDraftInGmail(to, title, contents) {
 
  var forScope = GmailApp.getInboxUnreadCount(); // needed for auth scope
  var htmlBody = "<p>Hello, I am an HTML message</p><hr>";
 
 var mail = [
        "To: $to",
        "Subject: =?utf-8?B?$subject?=",
        "MIME-Version: 1.0",
        "Content-Type: text/plain; charset=UTF-8",
        "Content-Transfer-Encoding: 7bit",
        "",
        "$body"
      ].join("\n").trim();
   mail = mail
  .replace("$to", to)
  .replace("$subject", Utilities.base64Encode(title.getContentText("shift-jis")))
  .replace("$body", contents);
  var encoded = Utilities.base64Encode(unescape(encodeURIComponent(mail)))
  .replace(/\+/g, '-').replace(/\//g, '_');
  
  var params = {
    method      : "post",
    contentType : "application/json",
    headers     : {"Authorization": "Bearer " + ScriptApp.getOAuthToken()},
    muteHttpExceptions:true,
    payload:JSON.stringify({
      "message": {
        "raw": encoded
      }
    })
  };
 
  var resp = UrlFetchApp.fetch("https://www.googleapis.com/gmail/v1/users/me/drafts", params);
  Logger.log(resp.getContentText());
}

function fromISOJP(str){
  var blob = Utilities.newBlob("");
  blob.setDataFromString(str, "JIS");
  return blob.getDataAsString();
}

function createDraft(to, subject, body) {
  Logger.log(to);
var forScope = GmailApp.getInboxUnreadCount(); // needed for auth scope
  subject = "=?ISO-2022-JP?B?" + Utilities.base64Encode(fromISOJP(subject))+ "?=";
  body = fromISOJP(body);


  var raw = 
      'Subject:' + subject + '\n' + 
      'To: ' + to + '\n' +
      'MIME-Version: 1.0\n' +
      'Content-Type: text/plain; charset=ISO-2022-JP; format=flowed; delsp=yes \n' +
      'Content-Transfer-Encodeing: 7bit\n\n'+
      body + '\n'

  var draftBody = Utilities.base64EncodeWebSafe(raw);

  var params = {method:"post",
                contentType: "application/json",
                headers: {"Authorization": "Bearer " + ScriptApp.getOAuthToken()},
                muteHttpExceptions:true,
                payload:JSON.stringify({
                  "message": {
                    "raw": draftBody
                  }
                })
               };

  var resp = UrlFetchApp.fetch("https://www.googleapis.com/gmail/v1/users/me/drafts", params);
  Logger.log(resp.getContentText());
  /*
   * sample resp: {
   *   "id": "r3322255254535847929",
   *   "message": {
   *     "id": "146d6ec68eb36de8",
   *     "threadId": "146d6ec68eb36de8",
   *     "labelIds": [ "DRAFT" ]
   *   }
   * }
   */
}