Google Script for Google Sheets mass emailing

google_sheets_emailer.js

// modified from https://developers.google.com/apps-script/articles/sending_emails#section2, cf https://developers.google.com/site-policies
// Licensed under Apache 2.0 License http://www.apache.org/licenses/LICENSE-2.0,
// Copyright (c) Google Inc, MathJax Consortium
// 

function sendEmails() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var startRow = 1;  // First row of data to process
  var numRows = 1;   // Number of rows to process
  // Fetch the range of cells
  var dataRange = sheet.getRange(startRow, 1, numRows, 2) // getRange(row, column, numRows, numColumns) 
  // Fetch values for each row in the Range.
  var data = dataRange.getValues();
  for (var i = 0; i < data.length; ++i) {
    var row = data[i];
    var name = row[0];  // First column
    var emailAddress = row[1];  // Second column
    var subject = "subject line";
    var message = 'Dear '+ name +',\n\n' // the actual message
      + 'moar lines.\n\n' // or else       
    if (sheet.getRange(startRow + i, 3).isBlank()) {  // Prevents sending duplicates
      MailApp.sendEmail(emailAddress, subject, message);
      var d = new Date();
      sheet.getRange(startRow + i, 3).setValue(d.toLocaleTimeString()); // record time of the email
      // Make sure the cell is updated right away in case the script is interrupted
      SpreadsheetApp.flush();
    }
  }
}