diff --git a/core/modules/user/config/schema/user.schema.yml b/core/modules/user/config/schema/user.schema.yml
index 23a688a..82cd45c 100644
--- a/core/modules/user/config/schema/user.schema.yml
+++ b/core/modules/user/config/schema/user.schema.yml
@@ -13,6 +13,9 @@ user.settings:
     verify_mail:
       type: boolean
       label: 'Require e-mail verification when a visitor creates an account.'
+    verify_email_match:
+      type: boolean
+      label: 'Require e-mail and username match when e-mail is used as username.'
     notify:
       type: mapping
       label: 'Notify user'
diff --git a/core/modules/user/config/user.settings.yml b/core/modules/user/config/user.settings.yml
index fbb0d98..742a6b3 100644
--- a/core/modules/user/config/user.settings.yml
+++ b/core/modules/user/config/user.settings.yml
@@ -1,6 +1,7 @@
 admin_role: ''
 anonymous: Anonymous
 verify_mail: true
+verify_email_match: true
 notify:
   cancel_confirm: true
   password_reset: true
diff --git a/core/modules/user/lib/Drupal/user/AccountFormController.php b/core/modules/user/lib/Drupal/user/AccountFormController.php
index fa8635c..a1d43bf 100644
--- a/core/modules/user/lib/Drupal/user/AccountFormController.php
+++ b/core/modules/user/lib/Drupal/user/AccountFormController.php
@@ -341,7 +341,7 @@ public function validate(array $form, array &$form_state) {
 
         // Check whether the user name provided is an email address, if so, make
         // sure it matches the mail value.
-        if (filter_var($name, FILTER_VALIDATE_EMAIL) && ($name !== $mail)) {
+        if (\Drupal::config('user.settings')->get('verify_email_match') && (filter_var($name, FILTER_VALIDATE_EMAIL) && ($name !== $mail))) {
           $this->setFormError('name', $form_state, $this->t('If your username is an email address, it must match your email.'));
         }
       }
diff --git a/core/modules/user/lib/Drupal/user/AccountSettingsForm.php b/core/modules/user/lib/Drupal/user/AccountSettingsForm.php
index cc4e255..374ae6b 100644
--- a/core/modules/user/lib/Drupal/user/AccountSettingsForm.php
+++ b/core/modules/user/lib/Drupal/user/AccountSettingsForm.php
@@ -129,6 +129,12 @@ public function buildForm(array $form, array &$form_state) {
       '#default_value' => $config->get('verify_mail'),
       '#description' => $this->t('New users will be required to validate their e-mail address prior to logging into the site, and will be assigned a system-generated password. With this setting disabled, users will be logged in immediately upon registering, and may select their own passwords during registration.')
     );
+    $form['registration_cancellation']['user_email_match_verification'] = array(
+      '#type' => 'checkbox',
+      '#title' => $this->t('Require e-mail and username match when e-mail is used as username.'),
+      '#default_value' => $config->get('verify_email_match'),
+      '#description' => $this->t('Users will be required to have matching e-mail address and username if an email address is used as username.')
+    );
     $form['registration_cancellation']['user_password_strength'] = array(
       '#type' => 'checkbox',
       '#title' => $this->t('Enable password strength indicator'),
@@ -415,6 +421,7 @@ public function submitForm(array &$form, array &$form_state) {
       ->set('register', $form_state['values']['user_register'])
       ->set('password_strength', $form_state['values']['user_password_strength'])
       ->set('verify_mail', $form_state['values']['user_email_verification'])
+      ->set('verify_email_match', $form_state['values']['user_email_match_verification'])
       ->set('signatures', $form_state['values']['user_signatures'])
       ->set('cancel_method', $form_state['values']['user_cancel_method'])
       ->set('notify.status_activated', $form_state['values']['user_mail_status_activated_notify'])
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserEditedOwnAccountTest.php b/core/modules/user/lib/Drupal/user/Tests/UserEditedOwnAccountTest.php
index 7726168..d5d30ea 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserEditedOwnAccountTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserEditedOwnAccountTest.php
@@ -57,5 +57,13 @@ function testUserEditedOwnAccount() {
     $edit['name'] = $account->getEmail();
     $this->drupalPostForm('user/' . $account->id() . '/edit', $edit, t('Save'));
     $this->assertText(t('The changes have been saved.'), 'The user account was saved.');
+
+    // Test that 'verify_email_match' turned off allows emails that don't match.
+    \Drupal::config('user.settings')->set('verify_email_match', FALSE)->save();
+
+    // Change username to my email address.
+    $edit['name'] = $this->randomName() . '@example.com';
+    $this->drupalPostForm('user/' . $account->id() . '/edit', $edit, t('Save'));
+    $this->assertText(t('The changes have been saved.'), 'The user account was saved.');
   }
 }
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserRegistrationTest.php b/core/modules/user/lib/Drupal/user/Tests/UserRegistrationTest.php
index 4c2761e..1de9afa 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserRegistrationTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserRegistrationTest.php
@@ -185,7 +185,32 @@ function testRegistrationEmailAsUsername() {
     $accounts = \Drupal::entityManager()->getStorageController('user')->loadByProperties(array('name' => $edit['name']));
     $new_user = reset($accounts);
     $this->assertTrue(($new_user->getUsername() === $edit['name']) && ($new_user->getEmail() === $edit['mail']), 'Created user with matching username and email address.');
+  }
+
+  /**
+   * Tests new users username not matching their email if username is an email.
+   */
+  function testRegistrationEmailAsUsernameDisabled() {
+    // Test that 'verify_email_match' turned off allows emails that don't match.
+    \Drupal::config('user.settings')
+      ->set('verify_email_match', FALSE)
+      ->set('verify_mail', FALSE)
+      ->set('register', USER_REGISTER_VISITORS)
+      ->save();
+
+    $mail = $this->randomName() . '@example.com';
+    $different = $this->randomName() . $mail;
 
+    $edit = array();
+    $edit['mail'] = $mail;
+    $edit['name'] = $different;
+    $edit['pass[pass1]'] = $edit['pass[pass2]'] = $this->randomName();
+
+    // Attempt to create an account using an email that doesn't match the name.
+    // This should be OK, as 'verify_email_match' is disabled.
+    $this->drupalPostForm('user/register', $edit, t('Create new account'));
+    $this->assertNoText(t('If your username is an email address, it must match your email.'), 'Email username does not match user email error message found.');
+    $this->assertText(t('Registration successful. You are now logged in.'), 'The user was not created and logged in.');
   }
 
   function testRegistrationDefaultValues() {