diff --git a/core/lib/Drupal/Core/Action/Plugin/Action/EmailAction.php b/core/lib/Drupal/Core/Action/Plugin/Action/EmailAction.php
index b345418..a1e4426 100644
--- a/core/lib/Drupal/Core/Action/Plugin/Action/EmailAction.php
+++ b/core/lib/Drupal/Core/Action/Plugin/Action/EmailAction.php
@@ -190,9 +190,16 @@ class EmailAction extends ConfigurableActionBase implements ContainerFactoryPlug
    * {@inheritdoc}
    */
   public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
-    if (!$this->emailValidator->isValid($form_state->getValue('recipient')) && strpos($form_state->getValue('recipient'), ':mail') === FALSE) {
-      // We want the literal %author placeholder to be emphasized in the error message.
-      $form_state->setErrorByName('recipient', t('Enter a valid email address or use a token email address such as %author.', ['%author' => '[node:author:mail]']));
+    if ($recipients = explode(',', $form_state->getValue('recipient')) || $recipients = explode(', ', $form_state->getValue('recipient'))) {
+      foreach ($recipients as $recipient) {
+        if (!$this->emailValidator->isValid($recipient) && strpos($recipient, ':mail') === FALSE) {
+          // We want the literal %author placeholder to be emphasized in the error
+          // message.
+          $form_state->setErrorByName('recipient', $this->t('Enter a valid email address or use a token email address such as %author.', [
+          '%author' => '[node:author:mail]',
+        ]));
+        }
+      }
     }
   }
 
diff --git a/core/tests/Drupal/KernelTests/Core/Action/EmailActionTest.php b/core/tests/Drupal/KernelTests/Core/Action/EmailActionTest.php
index 5c898f9..81d8aad 100644
--- a/core/tests/Drupal/KernelTests/Core/Action/EmailActionTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Action/EmailActionTest.php
@@ -62,39 +62,4 @@ class EmailActionTest extends KernelTestBase {
     $this->assertEquals('test@example.com', $variables['%recipient']);
   }
 
-  /**
-   * Tests multiple recipient email action plugin.
-   */
-  public function testMultipleRecipientsEmailAction() {
-    /** @var \Drupal\Core\Action\ActionManager $plugin_manager */
-    $plugin_manager = $this->container->get('plugin.manager.action');
-    $configuration = [
-      'recipient' => 'test@example.com, test+2@example.com, test+3@example.com',
-      'subject' => 'Test subject',
-      'message' => 'Test message',
-    ];
-    $plugin_manager
-      ->createInstance('action_send_email_action', $configuration)
-      ->execute();
-
-    $mails = $this->getMails();
-    $this->assertCount(1, $this->getMails());
-    $this->assertEquals('test@example.com, test+2@example.com, test+3@example.com', $mails[0]['to']);
-    $this->assertEquals('Test subject', $mails[0]['subject']);
-    $this->assertEquals("Test message\n", $mails[0]['body']);
-
-    // Ensure that the email sending is logged.
-    $log = \Drupal::database()
-      ->select('watchdog', 'w')
-      ->fields('w', ['message', 'variables'])
-      ->orderBy('wid', 'DESC')
-      ->range(0, 1)
-      ->execute()
-      ->fetch();
-
-    $this->assertEquals('Sent email to %recipient', $log->message);
-    $variables = unserialize($log->variables);
-    $this->assertEquals('test@example.com, test+2@example.com, test+3@example.com', $variables['%recipient']);
-  }
-
 }