onEdit sendEmail script

function sendEmail() {
  var checkboxRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet1").getRange("A1");
  var checkbox = checkboxRange.getValue();
  // Check checkbox is checked
  if (checkboxRange.isChecked()){
    // Fetch the email address
    var emailRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet1").getRange("B1");
    var emailAddress = emailRange.getValue();
    // Send Alert Email.
    var message = 'ENTER YOUR EMAIL MESSAGE HERE'; // Second column
    var subject = 'ENTER YOUR EMAIL SUBJECT HERE';
    MailApp.sendEmail(emailAddress, subject, message);
    }
};

function onEdit(e) {

  var ss = SpreadsheetApp.getActiveSheet();
  var r = ss.getActiveCell();
  if(r.getColumn() == 1 && ss.getName() == 'Sheet1') {
    sendEmail();
  }
};