From 2f0af94d33aeb0838d0095574730f39bf8989d54 Mon Sep 17 00:00:00 2001
From: Arnt Gulbrandsen <arnt@gulbrandsen.priv.no>
Date: Wed, 23 Oct 2024 15:34:11 +0200
Subject: [PATCH] Set UseSMTPUTF8 fully automatically when needed

This makes SMTPUTF8 support the default when the user chooses to use UTF-8
as charset, without affecting code that uses ISO 8859-1.
---
 src/PHPMailer.php                | 21 ++++++++++++++++++
 test/PHPMailer/PHPMailerTest.php | 38 +++++++++++++++++++++++++-------
 2 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index e5840ebb..5417d507 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -580,6 +580,10 @@ class PHPMailer
      * May be a callable to inject your own validator, but there are several built-in validators.
      * The default validator uses PHP's FILTER_VALIDATE_EMAIL filter_var option.
      *
+     * If CharSet is UTF8, the validator is left at the default value,
+     * and you send to addresses that use non-ASCII locallparts, then
+     * PHPMailer automatically changes to the 'eai' validator.
+     *
      * @see PHPMailer::validateAddress()
      *
      * @var string|callable
@@ -1168,6 +1172,11 @@ class PHPMailer
      */
     protected function addAnAddress($kind, $address, $name = '')
     {
+        if ($this->CharSet === self::CHARSET_UTF8 &&
+            self::$validator === 'php' &&
+            $this->addressHasUnicodeLocalpart($address)) {
+            self::$validator = 'eai';
+        }
         if (!in_array($kind, ['to', 'cc', 'bcc', 'Reply-To'])) {
             $error_message = sprintf(
                 '%s: %s',
@@ -4343,6 +4352,18 @@ class PHPMailer
         return false;
     }
 
+    /**
+     * Check whether the message requires SMTPUTF8 based on what's
+     * known so far.
+     *
+     * @return bool
+     */
+    public function needsSMTPUTF8()
+    {
+        return $this->UseSMTPUTF8;
+    }
+
+
     /**
      * Get an error message in the current language.
      *
diff --git a/test/PHPMailer/PHPMailerTest.php b/test/PHPMailer/PHPMailerTest.php
index 671a021c..15693a0a 100644
--- a/test/PHPMailer/PHPMailerTest.php
+++ b/test/PHPMailer/PHPMailerTest.php
@@ -1193,13 +1193,33 @@ EOT;
     }
 
     /**
-     * Test SMTPUTF8 usage, including when it is not to be used.
+     * Test that validation doesn't accidentally succeed.
      */
     public function testUnsupportedSmtpUTF8()
     {
+        $this->Mail = new PHPMailer(true);
         $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
         PHPMailer::$validator = 'html5';
-        self::assertFalse($this->Mail->addAddress('spın̈altap@example.com', ''));
+        self::assertFalse(PHPMailer::validateAddress('spın̈altap@example.com'));
+        PHPMailer::$validator = 'eai';
+        self::assertTrue(PHPMailer::validateAddress('spın̈altap@example.com'));
+    }
+
+    /**
+     * Test that SMTPUTF8 is automatically allowed if charset is UTF8.
+     */
+    public function testAutomaticEaiValidation()
+    {
+        $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
+
+        $this->Mail = new PHPMailer(true);
+        PHPMailer::$validator = 'php';
+        $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
+        $this->Mail->Body = 'Test';
+        $this->Mail->isSMTP();
+        self::assertTrue($this->Mail->addAddress('spın̈altap@example.com', ''));
+        $this->Mail->preSend();
+        self::assertTrue($this->Mail->needsSMTPUTF8());
     }
 
     /**
@@ -1207,24 +1227,26 @@ EOT;
      */
     public function testSmtpUTF8()
     {
-        //No reason to use SMTPUTF8
+        PHPMailer::$validator = "eai";
+        $this->Mail = new PHPMailer(true);
+        $this->Mail->Body = 'Test';
         $this->Mail->isSMTP();
         $this->Mail->addAddress('foo@example.com', '');
         $this->Mail->preSend();
+        self::assertFalse($this->Mail->needsSMTPUTF8());
 
         //Using a punycoded domain does not need SMTPUTF8
-        self::assertFalse($this->Mail->UseSMTPUTF8);
+        self::assertFalse($this->Mail->needsSMTPUTF8());
+        PHPMailer::$validator = "eai";
         $this->Mail->addAddress('foo@spın̈altap.example', '');
         $this->Mail->preSend();
-        self::assertFalse($this->Mail->UseSMTPUTF8);
+        self::assertFalse($this->Mail->needsSMTPUTF8());
 
         //Need to use SMTPUTF8, and can.
         $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
-        PHPMailer::$validator = 'eai';
-        self::assertTrue(PHPMailer::validateAddress('spın̈altap@example.com'));
         self::assertTrue($this->Mail->addAddress('spın̈altap@example.com', ''));
         $this->Mail->preSend();
-        self::assertTrue($this->Mail->UseSMTPUTF8);
+        self::assertTrue($this->Mail->needsSMTPUTF8());
 
         //If using SMTPUTF8, then the To header should contain
         //Unicode@Unicode, for better rendering by clients like Mac