diff --git a/publish/mail.php b/publish/mail.php
index 57b54b0..b45e0a1 100644
--- a/publish/mail.php
+++ b/publish/mail.php
@@ -75,7 +75,6 @@
         ],
 
         'log' => [
-            'dsn' => 'log://',
             'transport' => \HyperfExt\Mail\Transport\LogTransport::class,
             'options' => [
                 'name' => 'mail.local',
diff --git a/src/MailManager.php b/src/MailManager.php
index 374140c..6d83a1c 100644
--- a/src/MailManager.php
+++ b/src/MailManager.php
@@ -99,12 +99,12 @@ public function send(MailableInterface $mailable): void
      */
     protected function createTransport(array $config): TransportInterface
     {
-        if (empty($config['dsn'])) {
-            throw new InvalidArgumentException('The mail transport DSN must be specified.');
+        if (!empty($config['transport'])) {
+            return make($config['transport'], ['options' => $config['options'] ?? []]);
         }
 
-        if ($config['dsn'] === 'log://') {
-            return make($config['transport'], ['options' => $config['options'] ?? []]);
+        if (empty($config['dsn'])) {
+            throw new InvalidArgumentException('The mail transport DSN must be specified.');
         }
 
         $logger = null;
diff --git a/src/Mailable.php b/src/Mailable.php
index 2488d54..b9b7e5c 100644
--- a/src/Mailable.php
+++ b/src/Mailable.php
@@ -493,7 +493,8 @@ protected function hasRecipient(
 
     protected function buildView(array $data): array
     {
-        Coroutine::create(function () use ($data, &$html, &$plain) {
+        $chan = new \Swoole\Coroutine\Channel(1);
+        Coroutine::create(function () use ($data, $chan) {
             if (! empty($this->locale)) {
                 ApplicationContext::getContainer()->get(TranslatorInterface::class)->setLocale($this->locale);
             }
@@ -511,9 +512,11 @@ protected function buildView(array $data): array
             } elseif (! empty($this->textViewTemplate)) {
                 $plain = $this->renderView($this->textViewTemplate, $data);
             }
+
+            $chan->push([$html, $plain]);
         });
 
-        return [$html, $plain];
+        return $chan->pop();
     }
 
     /**