Issue #3418117: Deprecated function: Creation of dynamic property...

Issue #3418117: Deprecated function: Creation of dynamic property Drupal\symfony_mailer\Email::$_symfony_mailer_log

Closes #3418117

src/Plugin/EmailAdjuster/LogMail.php

@@ -33,6 +33,13 @@ class LogMail extends EmailAdjusterBase implements ContainerFactoryPluginInterfa
    */
   protected $symfonyMailLogStorage;
 
+  /**
+   * The log of the e-mail being processed.
+   *
+   * @var \Drupal\symfony_mailer_log\Entity\SymfonyMailerLog
+   */
+  protected $log;
+
   /**
    * Creates an email adjuster plugin for using Maillog via Symfony Mailer.
    *
@@ -86,10 +93,9 @@ class LogMail extends EmailAdjusterBase implements ContainerFactoryPluginInterfa
       ]);
       $log->save();
 
-      // Store the log entity on the $email so we can update it later when the
-      // 'errorMessage' is set (or left unset) after attempting to actually send
-      // the email.
-      $email->_symfony_mailer_log = $log;
+      // Store the log entity on so it can updated later when the 'errorMessage'
+      // is set (or left unset) after attempting to actually send the email.
+      $this->log = $log;
     }
     catch (\Exception $ex) {
       $this->getLogger('symfony_mail_log')->error($ex->getMessage());
@@ -103,12 +109,13 @@ class LogMail extends EmailAdjusterBase implements ContainerFactoryPluginInterfa
    *   The email to process.
    */
   public function postSend(EmailInterface $email) {
-    if ($log = $email->_symfony_mailer_log) {
+    if ($log = $this->log) {
       if ($errorMessage = $email->getError()) {
         $log->setErrorMessage(substr($errorMessage, 0, 255));
       }
       $log->save();
     }
+    $this->log = NULL;
   }
 
   /**