Ticket #9913: 9913.diff

Index: wp-includes/pluggable.php
===================================================================
--- wp-includes/pluggable.php   (revision 11438)
+++ wp-includes/pluggable.php   (working copy)
@@ -249,9 +249,10 @@
  * @param string $message Message contents
  * @param string|array $headers Optional. Additional headers.
  * @param string|array $attachments Optional. Files to attach.
+ * @param bool $preserve_quotes Optional. Preserve encoded quotes in plain text emails.
  * @return bool Whether the email contents were sent successfully.
  */
-function wp_mail( $to, $subject, $message, $headers = '', $attachments = array() ) {
+function wp_mail( $to, $subject, $message, $headers = '', $attachments = array(), $preserve_quotes = false ) {
        // Compact the input, apply the filters, and extract them back out
        extract( apply_filters( 'wp_mail', compact( 'to', 'subject', 'message', 'headers', 'attachments' ) ) );
 
@@ -337,6 +338,14 @@
                }
        }
 
+       if ( $preserve_quotes != true && ( !isset( $content_type ) || $content_type = 'text/plain' ) ) {
+               // Ensure we don't send encoded quotes in plain text emails
+               $encoded_quotes = array( '"', ''' );
+               $decoded_quotes = array( '"', "'" );
+               $subject = str_replace( $encoded_quotes, $decoded_quotes, $subject );
+               $message = str_replace( $encoded_quotes, $decoded_quotes, $message );
+       }
+
        // Empty out the values that may be set
        $phpmailer->ClearAddresses();
        $phpmailer->ClearAllRecipients();