diff --git a/src/Plugin/Mail/SMTPMailSystem.php b/src/Plugin/Mail/SMTPMailSystem.php
index ea884a1..bfa07ad 100644
--- a/src/Plugin/Mail/SMTPMailSystem.php
+++ b/src/Plugin/Mail/SMTPMailSystem.php
@@ -112,7 +112,7 @@ class SMTPMailSystem implements MailInterface {
         // If smtp_from config option is blank, use site_email.
         if (($from = $this->smtpConfig->get('site_mail')) == '') {
           drupal_set_message(t('There is no submitted from address.'), 'error');
-          watchdog('smtp', 'There is no submitted from address.', array(), WATCHDOG_ERROR);
+          \Drupal::logger('smtp')->error('There is no submitted from address.');
           return FALSE;
         }
       }
@@ -122,7 +122,7 @@ class SMTPMailSystem implements MailInterface {
 
     if (!\Drupal::service('email.validator')->isValid($from_comp['email'])) {
       drupal_set_message(t('The submitted from address (@from) is not valid.', array('@from' => $from)), 'error');
-      watchdog('smtp', 'The submitted from address (@from) is not valid.', array('@from' => $from), WATCHDOG_ERROR);
+      \Drupal::logger('smtp')->error(t('The submitted from address (@from) is not valid.'), array('@from' => $from));
       return FALSE;
     }
 
@@ -209,7 +209,7 @@ class SMTPMailSystem implements MailInterface {
             default:
               // Everything else is unsuppored by PHPMailer.
               drupal_set_message(t('The %header of your message is not supported by PHPMailer and will be sent as text/plain instead.', array('%header' => "Content-Type: $value")), 'error');
-              watchdog('smtp', 'The %header of your message is not supported by PHPMailer and will be sent as text/plain instead.', array('%header' => "Content-Type: $value"), WATCHDOG_ERROR);
+              \Drupal::logger('smtp')->error(t('The %header of your message is not supported by PHPMailer and will be sent as text/plain instead.', array('%header' => "Content-Type: $value")));
 
               // Force the Content-Type to be text/plain.
               $mailer->IsHTML(FALSE);
@@ -488,7 +488,7 @@ class SMTPMailSystem implements MailInterface {
       'from' => $from,
     );
     if ($this->smtpConfig->get('smtp_queue')) {
-      watchdog('smtp', 'Queue sending mail to: @to', array('@to' => $to));
+      \Drupal::logger('smtp')->info(t('Queue sending mail to: @to', array('@to' => $to)));
       smtp_send_queue($mailerArr);
     }
     else {