Ticket #28039: 28039.2.diff

src/wp-includes/class-phpmailer.php

@@ -1667 +1667 @@
     public function getMailMIME()
     {
         $result = '';
+        $ismultipart = true;
         switch ($this->message_type) {
             case 'inline':
                 $result .= $this->headerLine('Content-Type', 'multipart/related;');
@@ -1687 +1688 @@
             default:
                 // Catches case 'plain': and case '':
                 $result .= $this->textLine('Content-Type: ' . $this->ContentType . '; charset=' . $this->CharSet);
+                $ismultipart = false;
                 break;
         }
         //RFC1341 part 5 says 7bit is assumed if not specified
         if ($this->Encoding != '7bit') {
-            $result .= $this->headerLine('Content-Transfer-Encoding', $this->Encoding);
+            //RFC 2045 section 6.4 says multipart MIME parts may only use 7bit, 8bit or binary CTE
+            if ($ismultipart) {
+                if ($this->Encoding == '8bit') {
+                    $result .= $this->headerLine('Content-Transfer-Encoding', '8bit');
+                }
+                //The only remaining alternatives are quoted-printable and base64, which are both 7bit compatible
+            } else {
+                $result .= $this->headerLine('Content-Transfer-Encoding', $this->Encoding);
+            }
         }
 
         if ($this->Mailer != 'mail') {

tests/phpunit/tests/mail.php

@@ -190 +190 @@
                 // Fatal errors
                 $this->assertFalse( wp_mail( 'invalid.address', 'subject', 'body', '', array() ) );
         }
+
+        function wp_mail_quoted_printable( $mailer ) {
+                $mailer->Encoding = 'quoted-printable';
+        }
+
+        function wp_mail_set_text_message( $mailer ) {
+                $mailer->AltBody = 'Wörld';
+        }
+
+        /**
+         * > If an entity is of type "multipart" the Content-Transfer-Encoding is
+         * > not permitted to have any value other than "7bit", "8bit" or
+         * > "binary".
+         * http://tools.ietf.org/html/rfc2045#section-6.4
+         *
+         * > "Content-Transfer-Encoding: 7BIT" is assumed if the
+         * > Content-Transfer-Encoding header field is not present.
+         * http://tools.ietf.org/html/rfc2045#section-6.1
+         *
+         * @ticket 28039
+         */
+        function test_wp_mail_content_transfer_encoding_in_quoted_printable_multipart() {
+                add_action( 'phpmailer_init', array( $this, 'wp_mail_quoted_printable' ) );
+                add_action( 'phpmailer_init', array( $this, 'wp_mail_set_text_message' ) );
+
+                wp_mail(
+                        'user@example.com',
+                        'Hello',
+                        '<p><strong>Wörld</strong></p>',
+                        'Content-Type: text/html'
+                );
+
+                $this->assertNotContains( 'quoted-printable', $GLOBALS['phpmailer']->mock_sent[0]['header'] );
+        }
 }