You may need to use the HTML type of emails if the plain text one doesn’t work on PHPMailer. For example:
$emailInput = $_POST['email'];
$merchInput = $_POST['merch-input'];
$mail->isHTML(true);
$mail->Body = "
##
".$emailInput." , ".$merchInput."
##
";
$mail->AltBody = "It may not work when using a plain text client. Please upgrade to an HTML email client.";