sitemonitor.js

function checkURLs() {
  var errors = [];
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var rows = ss.getDataRange().getValues();
  for (i in rows) {
    var url = rows[i][0];
    try {
      UrlFetchApp.fetch(url);
    } catch (e) {
      // This error message parsing is gross, but it looks like 
      // http://productforums.google.com/forum/#!topic/apps-script/m_HOPHx64X8
      // won't be fixed any time soon.
      var parsedError = e.message.match(/returned code (\d+)\. Server response/)[1];
      errors.push(parsedError + ' - '+ url);
    }
  }
  if (errors.length) {
    var emailTo = Session.getActiveUser().getEmail();
    MailApp.sendEmail(emailTo, 'Sitemonitor Status', errors.join('\n'));
  }
}