Google App Script to use form data from spreadsheet to send personalised mails

Code.gs

/**
 * Sends non-duplicate emails with data from the current spreadsheet.
 */

// This constant is written in last column(10th in our case) for rows for which an email
// has been sent successfully.
var EMAIL_SENT = 'EMAIL_SENT';

function sendEmails() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var startRow = 2; // First row of data to process --------> set actual value to 8
  var numRows = 3; // Number of rows to process----------> set actual value to 57

  // Fetch the range of cells from columns 1 to 10 for the given rows
  var dataRange = sheet.getRange(startRow, 1, numRows, 10);
  // Fetch values for each row in the Range.
  var data = dataRange.getValues();
  Logger.log(data);
  for (var i = 0; i < data.length; ++i) {
    var row = data[i];
    var emailAddress = row[3]; // Fourth column
    var name = row[1]; // Second column
    var emailSent = row[9]; // tenth column
    
    var imageUrl = "https://images.theconversation.com/files/304864/original/file-20191203-67028-qfiw3k.jpeg?ixlib=rb-1.1.0&rect=638%2C2%2C795%2C745&q=45&auto=format&w=496&fit=clip";
    var imageBlob = UrlFetchApp
                         .fetch(imageUrl)
                         .getBlob()
                         .setName("imageBlob");
    var htmlBody =  "Hi " + name + "!<br>"+
              "This is just a testing mail. <br><br> <strong>Heading</strong><br>Some words bla bla bla<br>"+
                "<img src='cid:image1' align='middle'><br><br>"+
                "Regards<br>Liyana Sahir<br>";
    
    if (emailSent !== EMAIL_SENT) { // Prevents sending duplicates
      var subject = 'Onnum koodi! :)';
      MailApp.sendEmail({
        to: emailAddress,
        subject: subject,
        htmlBody: htmlBody,
        inlineImages:
        {
          image1: imageBlob
        }
      });
      
      sheet.getRange(startRow + i, 10).setValue(EMAIL_SENT);
      // Make sure the cell is updated right away in case the script is interrupted
      SpreadsheetApp.flush();
    }
  }
}