diff --git a/src/PHPMailer.php b/src/PHPMailer.php
index cd96258f..47dd3022 100644
--- a/src/PHPMailer.php
+++ b/src/PHPMailer.php
@@ -1174,10 +1174,10 @@ class PHPMailer
     {
         if (
             self::$validator === 'php' &&
-            $this->addressHasUnicodeLocalPart($address)
+            ((bool) preg_match('/[\x80-\xFF]/', $address))
         ) {
-            //The caller has not altered the validator, so assume that they want UTF-8 support
-            //instead of failing
+            //The caller has not altered the validator and is sending to an address
+            //with UTF-8, so assume that they want UTF-8 support instead of failing
             $this->CharSet = self::CHARSET_UTF8;
             self::$validator = 'eai';
         }
@@ -1467,9 +1467,9 @@ class PHPMailer
                  * @see https://en.wikipedia.org/wiki/International_email
                  */
                 return (bool) preg_match(
-                    '/^[a-zA-Z0-9.!#$%&\'*+\/=?^_`{|}~\x80-\xff-]+@[a-zA-Z0-9\x80-\xff](?:[a-zA-Z0-9\x80-\xff-]{0,61}' .
-                    '[a-zA-Z0-9\x80-\xff])?(?:\.[a-zA-Z0-9\x80-\xff]' .
-                    '(?:[a-zA-Z0-9\x80-\xff-]{0,61}[a-zA-Z0-9\x80-\xff])?)*$/sD',
+                    '/^[-\p{L}\p{N}\p{M}.!#$%&\'*+\/=?^_`{|}~]+@[\p{L}\p{N}\p{M}](?:[\p{L}\p{N}\p{M}-]{0,61}' .
+                    '[\p{L}\p{N}\p{M}])?(?:\.[\p{L}\p{N}\p{M}]' .
+                    '(?:[-\p{L}\p{N}\p{M}]{0,61}[\p{L}\p{N}\p{M}])?)*$/usD',
                     $address
                 );
             case 'php':
diff --git a/test/PHPMailer/PHPMailerTest.php b/test/PHPMailer/PHPMailerTest.php
index 889f364b..d2852230 100644
--- a/test/PHPMailer/PHPMailerTest.php
+++ b/test/PHPMailer/PHPMailerTest.php
@@ -1197,24 +1197,30 @@ EOT;
      */
     public function testUnsupportedSmtpUTF8()
     {
-        $this->Mail = new PHPMailer(true);
-        $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
-        PHPMailer::$validator = 'html5';
-        self::assertFalse(PHPMailer::validateAddress('spın̈altap@example.com'));
-        PHPMailer::$validator = 'eai';
-        self::assertTrue(PHPMailer::validateAddress('spın̈altap@example.com'));
+        self::assertFalse(PHPMailer::validateAddress('spın̈altap@example.com', 'html5'));
+        self::assertTrue(PHPMailer::validateAddress('spın̈altap@example.com', 'eai'));
     }
 
     /**
-     * Test that SMTPUTF8 is automatically allowed if charset is UTF8.
+     * The eai regex is complex and warrants a few extra tests.
+     */
+    public function testStrangeUnicodeEmailAddresses()
+    {
+        PHPMailer::$validator = 'eai';
+        self::assertTrue(PHPMailer::validateAddress('spın̈altap@example.com'));
+        self::assertTrue(PHPMailer::validateAddress('spın̈altap@spın̈altap.com'));
+        self::assertTrue(PHPMailer::validateAddress('दूकान@मेरी.दूकान.भारत'));
+        self::assertTrue(PHPMailer::validateAddress('慕田峪长城@慕田峪长城.网址'));
+        self::assertFalse(PHPMailer::validateAddress('慕田峪长城@慕田峪长城。网址'));
+    }
+
+    /**
+     * Test that SMTPUTF8 is allowed unless the caller has made a concious choice against.
      */
     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', ''));
@@ -1227,7 +1233,7 @@ EOT;
      */
     public function testSmtpUTF8()
     {
-        PHPMailer::$validator = 'eai';
+        PHPMailer::$validator = 'php';
         $this->Mail = new PHPMailer(true);
         $this->Mail->Body = 'Test';
         $this->Mail->isSMTP();
@@ -1235,15 +1241,13 @@ EOT;
         $this->Mail->preSend();
         self::assertFalse($this->Mail->needsSMTPUTF8());
 
-        //Using a punycoded domain does not need SMTPUTF8
+        //Using a punycodable domain does not need SMTPUTF8
         self::assertFalse($this->Mail->needsSMTPUTF8());
-        PHPMailer::$validator = 'eai';
         $this->Mail->addAddress('foo@spın̈altap.example', '');
         $this->Mail->preSend();
         self::assertFalse($this->Mail->needsSMTPUTF8());
 
         //Need to use SMTPUTF8, and can.
-        $this->Mail->CharSet = PHPMailer::CHARSET_UTF8;
         self::assertTrue($this->Mail->addAddress('spın̈altap@example.com', ''));
         $this->Mail->preSend();
         self::assertTrue($this->Mail->needsSMTPUTF8());