Mail body is going null while sending mail through smtp - php

Question

I am trying to send a mail-in php using SMTP. If I send the mail in the simple text then it's working perfectly but when I add HTML code like b,a tag in it then the mail is going but my body of the mail is empty.
$mail = new PHPMailer;
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = 'pushkarnabandhu.com'; // Specify main and backup SMTP servers
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username = SMTP_EMAIL; // SMTP username
$mail->Password = SMTP_PASSWORD; // SMTP password
$mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted
$mail->Port = 587; // TCP port to connect to
$mail->setFrom(SMTP_EMAIL, 'Virtual Music');
$mail->addAddress($_POST['email'],$_POST['name']); // Add a recipient
// $mail->addAddress('ellen#example.com'); // Name is optional
// $mail->addReplyTo('info#example.com', 'Information');
// $mail->addCC('cc#example.com');
// $mail->addBCC('bcc#example.com');
// $mail->addAttachment('/var/tmp/file.tar.gz'); // Add attachments
// $mail->addAttachment('/tmp/image.jpg', 'new.jpg'); // Optional name
$mail->isHTML(true); // Set email format to HTML
$mail->Subject = 'Email confirmation';
$mail->Body = "<b><a href='".ROOT."confirm/$$insert[verification_string]'></a></b>";
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';
if(!$mail->send()) {
echo 'Message could not be sent.';
echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
echo 'Message has been sent';
}