Changeset 61201 for trunk/src/wp-includes/pluggable.php

Timestamp:

11/11/2025 02:34:32 AM (4 months ago)

Author:

westonruter

Message:

Mail: Improve multipart message handling in wp_mail().

This improves how wp_mail() handles Content-Type headers for multipart messages, preventing cases where the header could be duplicated.

Developed in ​https://github.com/WordPress/wordpress-develop/pull/9500

Props SirLouen, gitlost, rmccue, westi, MattyRob, bgermann, nacin, SergeyBiryukov, dd32, MikeHansenMe, Kleor, kitchin, JeffMatson, abcd95, westonruter, christinecooper, JohnVieth, dawidadach, imokweb, ayeshrajans, lakshyajeet, tusharbharti, sajjad67.
Fixes #15448.

File:

• trunk/src/wp-includes/pluggable.php (modified) (3 diffs)

trunk/src/wp-includes/pluggable.php

@@ -175 +175 @@
      *              instead of PHPMailer's default validator.
      * @since 6.9.0 Added $embeds parameter.
+     * @since 6.9.0 Improved Content-Type header handling for multipart messages.
      *
      * @global PHPMailer\PHPMailer\PHPMailer $phpmailer
@@ -352 +353 @@
                                     $boundary = trim( str_replace( array( 'BOUNDARY=', 'boundary=', '"' ), '', $charset_content ) );
                                     $charset  = '';
+                                    if ( preg_match( '~^multipart/(\S+)~', $content_type, $matches ) ) {
+                                        $content_type = 'multipart/' . strtolower( $matches[1] ) . '; boundary="' . $boundary . '"';
+                                    }
                                 }
 
@@ -547 +551 @@
                     }
                 }
-            }
-
-            if ( false !== stripos( $content_type, 'multipart' ) && ! empty( $boundary ) ) {
-                $phpmailer->addCustomHeader( sprintf( 'Content-Type: %s; boundary="%s"', $content_type, $boundary ) );
             }
         }