Allow address properties to be reset with an empty array.

Allow an empty array to be used to reset an individual address property
to its original state.

Refs #11627

src/Mailer/Email.php

@@ -1012,6 +1012,12 @@ class Email implements JsonSerializable, Serializable
      */
     protected function _setEmailSingle($varName, $email, $name, $throwMessage)
     {
+        if ($email === []) {
+            $this->{$varName} = $email;
+
+            return $this;
+        }
+
         $current = $this->{$varName};
         $this->_setEmail($varName, $email, $name);
         if (count($this->{$varName}) !== 1) {

tests/TestCase/Mailer/EmailTest.php

@@ -551,6 +551,49 @@ class EmailTest extends TestCase
     }
 
     /**
+     * test reset addresses method
+     *
+     * @return void
+     */
+    public function testResetAddresses()
+    {
+        $this->Email->reset();
+        $this->Email
+            ->setFrom('cake@cakephp.org', 'CakePHP')
+            ->setReplyTo('replyto@cakephp.org', 'ReplyTo CakePHP')
+            ->setReadReceipt('readreceipt@cakephp.org', 'ReadReceipt CakePHP')
+            ->setReturnPath('returnpath@cakephp.org', 'ReturnPath CakePHP')
+            ->setTo('to@cakephp.org', 'To, CakePHP')
+            ->setCc('cc@cakephp.org', 'Cc CakePHP')
+            ->setBcc('bcc@cakephp.org', 'Bcc CakePHP');
+
+        $this->assertNotEmpty($this->Email->getFrom());
+        $this->assertNotEmpty($this->Email->getReplyTo());
+        $this->assertNotEmpty($this->Email->getReadReceipt());
+        $this->assertNotEmpty($this->Email->getReturnPath());
+        $this->assertNotEmpty($this->Email->getTo());
+        $this->assertNotEmpty($this->Email->getCc());
+        $this->assertNotEmpty($this->Email->getBcc());
+
+        $this->Email
+            ->setFrom([])
+            ->setReplyTo([])
+            ->setReadReceipt([])
+            ->setReturnPath([])
+            ->setTo([])
+            ->setCc([])
+            ->setBcc([]);
+
+        $this->assertEmpty($this->Email->getFrom());
+        $this->assertEmpty($this->Email->getReplyTo());
+        $this->assertEmpty($this->Email->getReadReceipt());
+        $this->assertEmpty($this->Email->getReturnPath());
+        $this->assertEmpty($this->Email->getTo());
+        $this->assertEmpty($this->Email->getCc());
+        $this->assertEmpty($this->Email->getBcc());
+    }
+
+    /**
      * testMessageId method
      *
      * @return void