From 2e805b2b99fe9987f514d385a6c8b2b6c4809226 Mon Sep 17 00:00:00 2001
From: SirLouen <sir.louen@gmail.com>
Date: Thu, 7 Aug 2025 17:57:57 +0200
Subject: [PATCH] Refresh for 28618

---
 src/wp-includes/pluggable.php        | 11 +++++++++++
 tests/phpunit/includes/functions.php | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index 1dbac5e1d707c..a977f9a4d0cdf 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -254,6 +254,17 @@ function wp_mail( $to, $subject, $message, $headers = '', $attachments = array()
 			require_once ABSPATH . WPINC . '/class-wp-phpmailer.php';
 			$phpmailer = new WP_PHPMailer( true );
 
+			/**
+ 	        * Filters the PHPMailer object.
+ 	        *
+ 	        * Allows plugins to override the PHPMailer class with one of their own if required.
+ 	        *
+ 	        * @since 6.9.0
+ 	        *
+ 	        * @param object $phpmailer A PHPMailer (or compatible) class.
+ 	        */
+ 	        $phpmailer = apply_filters( 'wp_phpmailer', $phpmailer );
+
 			$phpmailer::$validator = static function ( $email ) {
 				return (bool) is_email( $email );
 			};
diff --git a/tests/phpunit/includes/functions.php b/tests/phpunit/includes/functions.php
index 516727380c109..fa26df40c40c3 100644
--- a/tests/phpunit/includes/functions.php
+++ b/tests/phpunit/includes/functions.php
@@ -363,3 +363,14 @@ function _unhook_font_registration() {
 	remove_action( 'init', '_wp_register_default_font_collections' );
 }
 tests_add_filter( 'init', '_unhook_font_registration', 1000 );
+
+/**
+ * Ensure that PHPMailer is always a MockPHPMailer
+ *
+ * @param object $phpmailer The PHPMailer object.
+ * @return object The MockPHPMailer object.
+ */
+function _wp_phpmailer( $phpmailer ) {
+	return new MockPHPMailer();
+}
+tests_add_filter( 'wp_phpmailer', '_wp_phpmailer' );