Changeset 61131

Timestamp:

11/04/2025 05:18:55 PM (9 months 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 );
+        }
 }