I’m unsure as to why this app script is sending an email with only [object Object] as the whole email?

I’m not smart enough to figure this out.

function scriptattempt() {
  let sheet = SpreadsheetApp.getActiveSheet();
  let dataRange = sheet.getRange('A2:J');
  let data = dataRange.getValues(); 

  data.forEach((row, index) => {
    let [regnumber, siccode, sicname, companyname, e1, e2, filingdeadline, e3, email, emailSent] = row;
    if (!regnumber || !siccode || !sicname || !companyname || !filingdeadline || !email || emailSent === true) return;
    // Validate email address before sending the email

    if (!isValidEmail(email)) {
      Logger.log(`Invalid email address found in row ${index + 2,9}: ${email}`);
      return;
    }
let subject = `Upcoming Accounting deadline ${filingdeadline} for ${companyname}.`;
let body = `Dear Sir/Madam.<br><br>  

I hope this email finds you well.<br><br> 

We have been notified that your filing deadline is approaching and is due by ${filingdeadline}.<br><br> 

Text<br>
Text we are able to work with companies like you in the ${sicname} industry with efficiency and precision to ensure that you meet your deadlines on time.<br><br> 

Get in touch if you would like more information on how we can help you.<br><br> 

Warm Regards,`;

    
    // Send the email
    MailApp.sendEmail({to: email, subject, htmlbody: body});

    // Mark email as sent in column 
    sheet.getRange(index + 2, 10).setValue(true); // +2 because index is 0-based and data starts from row 2
  });
}

I’ve tried a few things but i cant seem to find what it isn’t recognising