App Script to add an "Events" label to GMail messages sent from Google Calendar.

README.md

Usage

1. Create an "Events" label in GMail
2. Go to script.google.com and create a new project.
3. Replace the contents of Code.gs with those from this gist
4. Create a trigger. Select processInbox as the function to run. Select "Time-driven" as the event source. Select "Hour timer" as the type of time based trigger. Select "Every hour" as the hour interval.

Code.gs

function threadHasLabel(thread, labelName) {
  var existingLabels = thread.getLabels();
  
  for (var i = 0; i < existingLabels.length; i++) {
    if (existingLabels[i].getName() === labelName) {
      return true;
    }
  }
  
  return false;
}

// Adds a label to the thread a message is a part of
// if it is not already present
function addLabel(message, labelName) {
  var thread = message.getThread();
  
  // Only add the label if it is not already on the thread
  if (threadHasLabel(thread, labelName)) {
    return;
  }
      
  var label = GmailApp.getUserLabelByName(labelName);
  
  if (label === undefined) {
    Logger.log('The label "' + labelName + '" does not exist');
    return;
  }

  thread.addLabel(label);
}

function processMessage(message) {
  var body = message.getRawContent();

  // Sender: Google Calendar <[email protected]>
  if (body.indexOf("Sender: Google Calendar") > -1) {
    addLabel(message, 'Events');
  }
}

function processInbox() {
  // Process all recent threads in the Inbox
  var threads = GmailApp.search('in:inbox');

  Logger.log('Processing ' + threads.length + ' emails.');
  
  for (var i = 0; i < threads.length; i++) {
    // Get all messages in a given thread
    var messages = threads[i].getMessages();

    for (var j = 0; j < messages.length; j++) {
      var message = messages[j];
      processMessage(message);
    }
  }
}