Sending individual emails to students with App Script

sendGradeEmails.gs

function sendGradeEmails() {
  var spreadSheet = SpreadsheetApp.getActiveSheet();
  var dataRange = spreadSheet.getDataRange();
  // Fetch values for each row in the Range.
  var data = dataRange.getValues();
  var template = "Dear {name},\n\n" +
    "Here are your total percentage points (out of 100) for Software Construction:\n" + 
      "Exam: {exam}%\n" +
      "Exercise: {exercise}%\n" +        
      "Total: {total}%\n" +        
      "Grade: {grade}";
  var subject = "Individual Points";  
  var replyTo = "someReplyEmail@ifi.uzh.ch";
  
  var length = data.length;
  var start = 4; // Start of the actual grade sheet (I know, kind of magic number)
  for (var i = start; i < length; i++) {
    (function(val) {
      var row = data[i];
      var body = template;
      
      var emailAddress = row[3];
      
      var templateReplacements = {
        'name' : row[2] + " " + row[1],
        'exam' : Math.round(row[4]*100, 2),
        'exercise' : row[5],
        'total' : Math.round(row[6], 2),
        'grade' : row[7],
        'email' : emailAddress
      }
      for (var key in templateReplacements) {
        body = body.replace('{' + key + '}', templateReplacements[key]);
      }
      Logger.log(emailAddress);
      Logger.log(body);
      MailApp.sendEmail(emailAddress, replyTo, subject, body);
    })(i);
  }
}