diff --git a/core/includes/mail.inc b/core/includes/mail.inc
index 1f7897e..cabf917 100644
--- a/core/includes/mail.inc
+++ b/core/includes/mail.inc
@@ -8,7 +8,7 @@
 /**
  * Auto-detect appropriate line endings for e-mails.
  *
- * $conf['mail_line_endings'] will override this setting.
+ * $settings['mail_line_endings'] will override this setting.
  */
 define('MAIL_LINE_ENDINGS', isset($_SERVER['WINDIR']) || strpos($_SERVER['SERVER_SOFTWARE'], 'Win32') !== FALSE ? "\r\n" : "\n");
 
@@ -217,13 +217,13 @@ function drupal_mail($module, $key, $to, $langcode, $params = array(), $from = N
  *   Drupal\Core\Mail\PhpMail implementation.
  *
  * The selection of a particular implementation is controlled via the variable
- * 'mail_system', which is a keyed array.  The default implementation
- * is the class whose name is the value of 'default-system' key. A more specific
- * match first to key and then to module will be used in preference to the
- * default. To specify a different class for all mail sent by one module, set
- * the class name as the value for the key corresponding to the module name. To
- * specify a class for a particular message sent by one module, set the class
- * name as the value for the array key that is the message id, which is
+ * 'system.mail.system', which is a keyed array.  The default implementation
+ * is the class whose name is the value of 'default' key. A more specific match
+ * first to key and then to module will be used in preference to the default. To
+ * specify a different class for all mail sent by one module, set the class
+ * name as the value for the key corresponding to the module name. To specify
+ * a class for a particular message sent by one module, set the class name as
+ * the value for the array key that is the message id, which is
  * "${module}_${key}".
  *
  * For example to debug all mail sent by the user module by logging it to a
@@ -231,7 +231,7 @@ function drupal_mail($module, $key, $to, $langcode, $params = array(), $from = N
  *
  * @code
  * array(
- *   'default-system' => 'Drupal\Core\Mail\PhpMail',
+ *   'default' => 'Drupal\Core\Mail\PhpMail',
  *   'user' => 'DevelMailLog',
  * );
  * @endcode
@@ -241,7 +241,7 @@ function drupal_mail($module, $key, $to, $langcode, $params = array(), $from = N
  *
  * @code
  * array(
- *   'default-system' => 'Drupal\Core\Mail\PhpMail',
+ *   'default' => 'Drupal\Core\Mail\PhpMail',
  *   'user' => 'DevelMailLog',
  *   'contact_page_autoreply' => 'DrupalDevNullMailSend',
  * );
@@ -260,13 +260,15 @@ function drupal_mail($module, $key, $to, $langcode, $params = array(), $from = N
  *   alter hook in drupal_mail() would have been {$module}_{$key}.
  *
  * @return Drupal\Core\Mail\MailInterface
+ *
+ * @throws \Exception
  */
 function drupal_mail_system($module, $key) {
   $instances = &drupal_static(__FUNCTION__, array());
 
   $id = $module . '_' . $key;
 
-  $configuration = variable_get('mail_system', array('default-system' => 'Drupal\Core\Mail\PhpMail'));
+  $configuration = config('system.mail')->get('system');
 
   // Look for overrides for the default class, starting from the most specific
   // id, and falling back to the module name.
@@ -277,7 +279,7 @@ function drupal_mail_system($module, $key) {
     $class = $configuration[$module];
   }
   else {
-    $class = $configuration['default-system'];
+    $class = $configuration['default'];
   }
 
   if (empty($instances[$class])) {
@@ -506,8 +508,9 @@ function drupal_html_to_text($string, $allowed_tags = NULL) {
       if (isset($casing)) {
         $chunk = $casing($chunk);
       }
+      $line_endings = settings()->get('mail_line_endings', MAIL_LINE_ENDINGS);
       // Format it and apply the current indentation.
-      $output .= drupal_wrap_mail($chunk, implode('', $indent)) . MAIL_LINE_ENDINGS;
+      $output .= drupal_wrap_mail($chunk, implode('', $indent)) . $line_endings;
       // Remove non-quotation markers from indentation.
       $indent = array_map('_drupal_html_to_text_clean', $indent);
     }
diff --git a/core/lib/Drupal/Core/Mail/PhpMail.php b/core/lib/Drupal/Core/Mail/PhpMail.php
index f5ec995..580a824 100644
--- a/core/lib/Drupal/Core/Mail/PhpMail.php
+++ b/core/lib/Drupal/Core/Mail/PhpMail.php
@@ -59,13 +59,13 @@ public function mail(array $message) {
     foreach ($message['headers'] as $name => $value) {
       $mimeheaders[] = $name . ': ' . mime_header_encode($value);
     }
-    $line_endings = variable_get('mail_line_endings', MAIL_LINE_ENDINGS);
+    $line_endings = settings()->get('mail_line_endings', MAIL_LINE_ENDINGS);
     // Prepare mail commands.
     $mail_subject = mime_header_encode($message['subject']);
     // Note: e-mail uses CRLF for line-endings. PHP's API requires LF
     // on Unix and CRLF on Windows. Drupal automatically guesses the
     // line-ending format appropriate for your system. If you need to
-    // override this, adjust $conf['mail_line_endings'] in settings.php.
+    // override this, adjust $settings['mail_line_endings'] in settings.php.
     $mail_body = preg_replace('@\r?\n@', $line_endings, $message['body']);
     // For headers, PHP's API suggests that we use CRLF normally,
     // but some MTAs incorrectly replace LF with CRLF. See #234403.
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 713839e..cdfd07b 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -838,7 +838,7 @@ protected function setUp() {
     $this->resetAll();
 
     // Use the test mail class instead of the default mail handler class.
-    variable_set('mail_system', array('default-system' => 'Drupal\Core\Mail\VariableLog'));
+    config('system.mail')->set('system', array('default' => 'Drupal\Core\Mail\VariableLog'))->save();
 
     drupal_set_time_limit($this->timeLimit);
     // Temporary fix so that when running from run-tests.sh we don't get an
diff --git a/core/modules/system/config/system.mail.yml b/core/modules/system/config/system.mail.yml
new file mode 100644
index 0000000..47316e1
--- /dev/null
+++ b/core/modules/system/config/system.mail.yml
@@ -0,0 +1,2 @@
+system:
+  default: 'Drupal\Core\Mail\PhpMail'
diff --git a/core/modules/system/lib/Drupal/system/Tests/Mail/HtmlToTextTest.php b/core/modules/system/lib/Drupal/system/Tests/Mail/HtmlToTextTest.php
index 5302c8d..f93b40f 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Mail/HtmlToTextTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Mail/HtmlToTextTest.php
@@ -348,11 +348,8 @@ public function testDrupalHtmlToTextParagraphs() {
   public function testVeryLongLineWrap() {
     $input = 'Drupal<br /><p>' . str_repeat('x', 2100) . '</><br />Drupal';
     $output = drupal_html_to_text($input);
-    // This awkward construct comes from includes/mail.inc lines 8-13.
-    $eol = variable_get('mail_line_endings', MAIL_LINE_ENDINGS);
-    // We must use strlen() rather than drupal_strlen() in order to count
-    // octets rather than characters.
-    $line_length_limit = 1000 - drupal_strlen($eol);
+    $eol = settings()->get('mail_line_endings', MAIL_LINE_ENDINGS);
+
     $maximum_line_length = 0;
     foreach (explode($eol, $output) as $line) {
       // We must use strlen() rather than drupal_strlen() in order to count
diff --git a/core/modules/system/lib/Drupal/system/Tests/Mail/MailTest.php b/core/modules/system/lib/Drupal/system/Tests/Mail/MailTest.php
index bb72d29..9ca7277 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Mail/MailTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Mail/MailTest.php
@@ -42,7 +42,7 @@ function setUp() {
     parent::setUp();
 
     // Set MailTestCase (i.e. this class) as the SMTP library
-    variable_set('mail_system', array('default-system' => 'Drupal\system\Tests\Mail\MailTest'));
+    config('system.mail')->set('system.default', 'Drupal\system\Tests\Mail\MailTest')->save();
   }
 
   /**
@@ -119,4 +119,3 @@ public function mail(array $message) {
     self::$sent_message = $message;
   }
 }
-
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index b632a2f..f47af87 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -2324,6 +2324,17 @@ function system_update_8045() {
 }
 
 /**
+ * Converts mail settings to config.
+ *
+ * @ingroup config_upgrade
+ */
+function system_update_8046() {
+  update_variables_to_config('system.mail', array(
+    'mail_system' => 'system',
+  ));
+}
+
+/**
  * @} End of "defgroup updates-7.x-to-8.x".
  * The next series of updates should start at 9000.
  */