diff --git a/src/Email.php b/src/Email.php
index 6f9e068..74b246c 100644
--- a/src/Email.php
+++ b/src/Email.php
@@ -293,6 +293,7 @@ public function getLogs()
      */
     public function send()
     {
+        $message = null;
         $this->socket = fsockopen(
             $this->getServer(),
             $this->port,
@@ -346,7 +347,7 @@ public function send()
 
         if (!empty($this->attachments)) {
             $this->headers['Content-Type'] = 'multipart/mixed; boundary="mixed-' . $boundary . '"';
-            $message = '--mixed-' . $boundary . self::CRLF;
+            $message .= '--mixed-' . $boundary . self::CRLF;
             $message .= 'Content-Type: multipart/alternative; boundary="alt-' . $boundary . '"' . self::CRLF . self::CRLF;
         } else {
             $this->headers['Content-Type'] = 'multipart/alternative; boundary="alt-' . $boundary . '"';