post by email error Posted title: =?utf-8, wp-mail.php edit suggestions?

Hopefully someone can help me out here. My phone won’t allow me to change the type of email it send out so i cannot make it plain text.

With that in mind the error “Posted title: =?utf-8? etc” is generated by the wp-mail.php file. The content is fine it is only the subject that there is a problem with. The post is published so it is just literally the subject field that I am looking to correct. I spotted this bit of code on another site for an older version of wp but it no longer seems to work

if ($post_title == '') $post_title = $subject;

+ 	if (stripos($content_transfer_encoding, "base64") !== false) {
+ 		// $post_title might start with =?utf-8?B?
+ 		if (substr($post_title, 0, 10) == "=?utf-8?B?") {
+ 			$post_title = substr($post_title, 10);
+ 		}
+ 		$post_title = base64_decode($post_title);
+ 	}
+
  	if (empty($post_categories)) $post_categories[] = get_option('default_email_category');

  	$post_category = $post_categories;

thanks in advance for any advice offered.