diff --git a/src/Plugin/Mail/SymfonyMailer.php b/src/Plugin/Mail/SymfonyMailer.php
index db01470c6722b71f86538e840a065abb3761930e..c9761909295fc7a942dade0b1c226ee786fdcd6c 100644
--- a/src/Plugin/Mail/SymfonyMailer.php
+++ b/src/Plugin/Mail/SymfonyMailer.php
@@ -151,7 +151,7 @@ class SymfonyMailer implements MailInterface, ContainerFactoryPluginInterface {
     // Determine if a plain text alternative is required. The message parameter
     // takes priority over config. Support the alternate parameter 'convert'
     // for back-compatibility.
-    $generate_plain = TRUE; //$message['params']['generate_plain'] ?? $message['params']['convert'] ?? $this->config['message']['generate_plain'];
+    $generate_plain = !empty($message['params']['generate_plain']) || !empty($message['params']['convert']);
 
     if ($generate_plain && empty($message['plain']) && $is_html) {
       // Generate plain text alternative. This must be done first with the
diff --git a/symfony_mailer_lite.module b/symfony_mailer_lite.module
index eb3718d25de3e7d10d7b4e535dc956a824d1fb5b..eaf345cba55d77fbccafa4ff61e9a8a970aa029e 100644
--- a/symfony_mailer_lite.module
+++ b/symfony_mailer_lite.module
@@ -65,5 +65,6 @@ function symfony_mailer_lite_mail($key, &$message) {
     $message['body'] = array_map(function ($text) {
       return \Drupal\Core\Render\Markup::create($text);
     }, $text);
+    $message['params']['generate_plain'] = TRUE;
   }
 }