Adding Header to PHPMailer

I want to Below Header to my function , How and where to add it ?

$headers="";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=ISO-8859-1\r\n";

My Function is : ( Where and How to add above Lines )

function sendEmail($email,$subject, $message)
{

$mail = null;
$mail = new PHPMailer(true);
// $mail->IsSMTP();
try
{
$mail->Host = "Host"; // SMTP server
$mail->SMTPDebug = 0; // enables SMTP debug information (for testing)
$mail->SMTPAuth = true; // enable SMTP authentication
// sets the SMTP server
$mail->Port = 25; // set the SMTP port for the GMAIL server
$mail->Username ="username"; // SMTP account username
$mail->Password = "apaaa"; // SMTP account password
$mail->Priority = "1";
$mail->ConfirmReadingTo = "";

$mail->AddAddress($email);

$mail->SetFrom('', 'XXXX');
$mail->Subject = $subject;
$mail->MsgHTML($message);


if(!$mail->Send())
{
echo "Message could not be sent. <p>";
echo "Mailer Error: " . $mail->ErrorInfo;
exit;
}

//echo "Message has been sent";
}
catch (Exception $e)
{
echo $e;
}
$mail->ClearAllRecipients();
}
?>

 

PHPMailer has a feature to add custom headers as defined here:
https://phpmailer.github.io/PHPMailer/classes/PHPMailer.html#method_addCustomHeader

Examples:
$mail->addCustomHeader('X-custom-header', 'custom-value');
OR
$mail->addCustomHeader('X-custom-header: custom-value');

So for you, you can add:
$mail->addCustomHeader('MIME-Version: 1.0');
$mail->addCustomHeader('Content-Type: text/html; charset=ISO-8859-1');

 

Thanks a Lot.