Copy Email Messages in Gmail with Apps Script

April 15, 2017

This example shows how to create email copies in Gmail with Google Apps Script and the Gmail API. The requires requires authorization with the scope https://mail.google.com/ for reading Gmail drafts and composing new ones.

The uploadType is set to media and that will create the Gmail draft in a single HTTP request. However, if you are create a draft that includes big attachment, you may have to set the upload type as resumable to create the draft in at least two requests.

function duplicateGmailDrafts(count, draftId) {
  try {
    var draft = GmailApp.getMessageById(draftId);

    if (draft === null) {
      return 'Sorry, the draft message was not found. Please reload this page and try again.';
    }

    var gmailAPI = 'https://www.googleapis.com/upload/gmail/v1/users/me/drafts?uploadType=media';

    var params = {
      method: 'POST',
      contentType: 'message/rfc822',
      muteHttpExceptions: true,
      headers: {
        Authorization: 'Bearer ' + ScriptApp.getOAuthToken(),
      },
      payload: draft.getRawContent(),
    };

    for (var i = 0; i < count; i++) {
      UrlFetchApp.fetch(gmailAPI, params);
    }

    return 'Drafts Created';
  } catch (f) {
    return 'Error: ' + f.toString();
  }
}

Gmail Google Apps Script

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Amit Agarwal

Google Developer Expert, Google Cloud Champion

Amit Agarwal is a Google Developer Expert in Google Workspace and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India.

Amit has developed several popular Google add-ons including Mail Merge for Gmail and Document Studio. Read more on Lifehacker and YourStory