Changeset 61131

Timestamp:

11/04/2025 05:18:55 PM (10 days ago)

Author:

johnjamesjacoby

Message:

Mail: reset Encoding to 8-bit in wp_mail().

The PHPMailer library may automatically switch its encoding based on various internal factors.

This commit fixes a bug where the $phpmailer global was unintentionally persisting its Encoding property from the first wp_mail() call to all subsequent calls.

This includes unit tests to verify the fix is accurate, and a change to the mock-mailer helper that worked around this bug just-in-time when running the test suite.

Props codebuddy, dilip2615, rishabhwp, sajjad67, sirlouen, stephenharris.

Fixes #33972.

Location:

trunk

Files:

• src/wp-includes/pluggable.php (modified) (1 diff)
• tests/phpunit/includes/mock-mailer.php (modified) (1 diff)
• tests/phpunit/tests/pluggable/wpMail.php (modified) (1 diff)

trunk/src/wp-includes/pluggable.php

@@ -384 +384 @@
         $phpmailer->Body    = '';
         $phpmailer->AltBody = '';
+
+        /*
+         * Reset encoding to 8-bit, as it may have been automatically downgraded
+         * to 7-bit by PHPMailer (based on the body contents) in a previous call
+         * to wp_mail().
+         *
+         * See https://core.trac.wordpress.org/ticket/33972
+         */
+        $phpmailer->Encoding = PHPMailer\PHPMailer\PHPMailer::ENCODING_8BIT;
 
         // Set "From" name and email.

trunk/tests/phpunit/includes/mock-mailer.php

@@ -21 +21 @@
 
     public function preSend() {
-        $this->Encoding = '8bit';
         return parent::preSend();
     }

trunk/tests/phpunit/tests/pluggable/wpMail.php

@@ -652 +652 @@
         }
     }
+
+    /**
+     * Test that the encoding of the email does not bleed between long and short emails.
+     *
+     * @ticket 33972
+     */
+    public function test_wp_mail_encoding_does_not_bleed() {
+        $content = str_repeat( 'A', 1000 );
+        wp_mail( WP_TESTS_EMAIL, 'Looong line testing', $content );
+
+        $mailer = tests_retrieve_phpmailer_instance();
+        $this->assertEquals( 'quoted-printable', $mailer->Encoding );
+
+        wp_mail( WP_TESTS_EMAIL, 'A follow up short email', 'Short email' );
+
+        $mailer = tests_retrieve_phpmailer_instance();
+        $this->assertEquals( '7bit', $mailer->Encoding );
+    }
 }