Issue #3411420: Add error message field and logging in case sending the email fails.

src/Entity/SymfonyMailerLog.php

@@ -289,7 +289,27 @@ class SymfonyMailerLog extends ContentEntityBase implements SymfonyMailerLogInte
       ->setDescription(t('The time when the log entry was created.'))
       ->setDisplayConfigurable('view', TRUE);
 
+    $fields['error_message'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Error message'))
+      ->setRequired(FALSE)
+      ->setDescription(t('The error message if sending the email failed.'))
+      ->setDisplayConfigurable('view', TRUE);
+
     return $fields;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getErrorMessage(): string|null {
+    return $this->get('error_message');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setErrorMessage(string $errorMessage) {
+    $this->set('error_message', $errorMessage);
+  }
+
 }

src/Entity/SymfonyMailerLogInterface.php

@@ -137,4 +137,19 @@ interface SymfonyMailerLogInterface extends ContentEntityInterface {
    */
   public function setCreatedTime(int $timestamp): SymfonyMailerLogInterface;
 
+  /**
+   * Returns the error message if sending failed.
+   *
+   * @return string|null
+   *   The error message or null if there was no error sending the email.
+   */
+  public function getErrorMessage(): string|null;
+
+  /**
+   * Sets the error message if sending failed.
+   *
+   * @param $errorMessage
+   */
+  public function setErrorMessage(string $errorMessage);
+
 }

src/Plugin/EmailAdjuster/LogMail.php

@@ -85,12 +85,31 @@ class LogMail extends EmailAdjusterBase implements ContainerFactoryPluginInterfa
         'langcode' => $email->getLangcode(),
       ]);
       $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;
     }
     catch (\Exception $ex) {
       $this->getLogger('symfony_mail_log', $ex->getMessage());
     }
   }
 
+  /**
+   * React to EmailInterface::PHASE_POST_SEND.
+   *
+   * @param \Drupal\symfony_mailer\EmailInterface $email
+   *   The email to process.
+   */
+  public function postSend(EmailInterface $email) {
+    if ($log = $email->_symfony_mailer_log) {
+      if ($errorMessage = $email->getError())
+        $log->setErrorMessage(substr($errorMessage, 0, 255));
+      $log->save();
+    }
+  }
+
   /**
    * Render array of addresses as array of strings.
    *

symfony_mailer_log.install

+<?php
+
+use Drupal\Core\Field\BaseFieldDefinition;
+
+/**
+ * Adds the
+ */
+function symfony_mailer_log_update_9100() {
+  $field_storage_definition = BaseFieldDefinition::create('string')
+    ->setLabel(t('Error message'))
+    ->setRequired(FALSE)
+    ->setDescription(t('The error message if sending the email failed.'))
+    ->setDisplayConfigurable('view', TRUE);
+
+  \Drupal::entityDefinitionUpdateManager()
+    ->installFieldStorageDefinition('error_message', 'symfony_mailer_log', 'symfony_mailer_log', $field_storage_definition);
+}
+