Google sheet automatische emails

function onOpen() {

  var ss = SpreadsheetApp.getActive();

  var items = [

    {name: 'send now', functionName: 'sendEmails'}

  ];

  ss.addMenu('send Emails', items);

};

function sendEmails() {

  var sheet = SpreadsheetApp.getActiveSheet();

  var sheet2= SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Templates");

  var startRow = 2;  //Start Zeile

  var numRows = sheet2.getRange("A2").getValue(); //Formel zum Zählen der Zeilen

  var dataRange = sheet.getRange(startRow, 1, numRows, 24) // start und Anzahl der spalten

  var data = dataRange.getValues();

  for (var i = 0; i < data.length; ++i) {

  var row = data[i];

  var emailTo = row[4];

  var subject = "Hier kommt der Betreff rein";

  var options = {}

     options.htmlBody = "Text"

     ;

  MailApp.sendEmail(emailTo, subject, '', options);

  sheet.getRange(startRow + i, 12).setValue("Email_SENT");

  SpreadsheetApp.flush();

  }

}