I have a working script for creating a new Gmail draft but when I use createDraftReplyAll in an existing thread, it puts the sender of the last email of the thread as the recipient of the draft.

So if I sent the last email, I become the recipient of the reply, and the other party is Cc'd. And if the other person wrote the last email, they are the recipient but I get CC'd. This is not normal behavior compared with manually creating a draft in Gmail (i.e. from clicking Reply To All), in which case the recipient will always be the other party.

Shown here (result of running the script below):

And normal behavior from clicking Reply All in Gmail:

This is the function I use to create the draft. The thread has already been found via the Subject and original message date:

  function createDraftReplyInThread(emailThread, htmlTemplateFileName) {
  Logger.log(">> IN createDraftReplyInThread");
  Logger.log("htmlTemplateFileName: "   htmlTemplateFileName);

  if (emailThread) {
    let emailTo = emailThread.to;
    Logger.log('Thread TO: '   emailTo);
    let threadMessages = emailThread.getMessages();
    let messageCount = threadMessages.length;
    let lastMessage = threadMessages[messageCount - 1];

    let htmlTemplate = HtmlService.createTemplateFromFile(htmlTemplateFileName);
    let htmlBodyContent = htmlTemplate.evaluate().getContent();
    var myReplyID = lastMessage.createDraftReplyAll(
      "Plain text for draft reply (not used)",
      {
        'htmlBody': htmlBodyContent
      }).getId();

    Logger.log(`Draft created in thread; myReplyID: ${myReplyID}`);  // just to show it's executed okay

    return;
  }

  return null;
}

It's probably best to ignore this, but I did try to use the limited existing update methods to copy the content, change the recipient and reinstate the the content in a new draft (pure guess work). Noting that draft.update() does work to change the recipient but it also requires a Message argument which I failed to get to work. Possible?

// based off stackoverflow: https://stackoverflow.com/questions/54745999/modify-only-the-subject-and-send-the-draft
function _sandbox_draftModify() {

  var draft = GmailApp.getDrafts()[0];
  var draftAsMessage = draft.getMessage();
  var recipients = draftAsMessage.getTo();
  var subject = draftAsMessage.getSubject();
  var origRaw = draftAsMessage.getRawContent();
  var newRaw = origRaw.replace("new draft", "old draft");
  var newRawB64 = Utilities.base64EncodeWebSafe(newRaw, Utilities.Charset.UTF_8);

  var emailTo = '[email protected]';  
  Logger.log(`recipients: ${recipients}`);
  Logger.log(`subject: ${subject}`);
  Logger.log(`newRaw: ${newRaw}`);

  draft.update(emailTo, subject, { message: { raw: newRawB64 } });

  var draftNew = GmailApp.getDrafts()[0];
  userId = 'me';
  Gmail.Users.Drafts.update({ message: { raw: newRawB64 } }, userId, draftNew.getId());
  Logger.log("Done");
}

In the end all I need is to be able to create a draft email to an existing thread (which I can do already) but with the correct recipient(s), however that may be achieved.

CodePudding user response：

This seems to be the expected behavior for the createDraftReplyAll method.

If you check the documentation page here:

createDraftReplyAll(body)

Creates a draft message replying to the sender of the last message in this thread, using the reply-to address and all recipients of this message. The size of the email (including headers) is quota limited.

However, you can file a feature request on Issue Tracker if you would like to have a functionality which replicates the UI behavior. The form can be found at this link and make sure to fill in all the necessary information.

Reference

• Apps Script GmailThread Class - createDraftReplyAll().