diff --git a/src/Mailgun/Connection/RestClient.php b/src/Mailgun/Connection/RestClient.php
index af1dfe3..849b981 100644
--- a/src/Mailgun/Connection/RestClient.php
+++ b/src/Mailgun/Connection/RestClient.php
@@ -133,9 +133,10 @@ class RestClient
         $postDataMultipart = [];
         foreach ($postData as $key => $value) {
             if (is_array($value)) {
+                $index = 0;
                 foreach ($value as $subValue) {
                     $postDataMultipart[] = [
-                        'name'     => $key,
+                        'name'     => sprintf('%s[%d]', $key, $index++),
                         'contents' => $subValue,
                     ];
                 }
diff --git a/tests/Functional/NoSamePostNameTest.php b/tests/Functional/NoSamePostNameTest.php
index 0f346ff..cf16a8b 100644
--- a/tests/Functional/NoSamePostNameTest.php
+++ b/tests/Functional/NoSamePostNameTest.php
@@ -26,7 +26,10 @@ class NoSamePostNameTest extends \PHPUnit_Framework_TestCase
 
         $builder = $mailgun->MessageBuilder();
         $builder->setFromAddress("bob@example.com");
-        $builder->addToRecipient("alice@example.com");
+        $builder->addToRecipient("to1@example.com");
+        $builder->addToRecipient("tp2@example.com");
+        $builder->addBccRecipient("bcc1@example.com");
+        $builder->addBccRecipient("bcc2@example.com");
         $builder->setSubject("Foo");
         $builder->setTextBody("Bar");