diff --git a/src/Mailgun/Connection/RestClient.php b/src/Mailgun/Connection/RestClient.php
index 54d3a25..bab2acc 100644
--- a/src/Mailgun/Connection/RestClient.php
+++ b/src/Mailgun/Connection/RestClient.php
@@ -117,9 +117,11 @@ class RestClient{
 	public function responseHandler($responseObj){
 		$httpResponseCode = $responseObj->getStatusCode();
 		if($httpResponseCode === 200){
-			$jsonResponseData = json_decode($responseObj->getBody(), false);
+			$data = (string) $responseObj->getBody();
+			$jsonResponseData = json_decode($data, false);
 			$result = new \stdClass();
-			$result->http_response_body = $jsonResponseData;
+			// return response data as json if possible, raw if not
+			$result->http_response_body = $data && $jsonResponseData === null ? $data : $jsonResponseData;
 		}
 		elseif($httpResponseCode == 400){
 			throw new MissingRequiredParameters(EXCEPTION_MISSING_REQUIRED_PARAMETERS);
diff --git a/src/Mailgun/Messages/MessageBuilder.php b/src/Mailgun/Messages/MessageBuilder.php
index bf47871..34032bb 100644
--- a/src/Mailgun/Messages/MessageBuilder.php
+++ b/src/Mailgun/Messages/MessageBuilder.php
@@ -169,26 +169,22 @@ class MessageBuilder
 
     public function addAttachment($attachmentPath, $attachmentName = null)
     {
-        if (preg_match("/^@/", $attachmentPath)) {
-            if (isset($this->files["attachment"])) {
-                $attachment = array(
+        if (isset($this->files["attachment"])) {
+            $attachment = array(
+                'filePath'   => $attachmentPath,
+                'remoteName' => $attachmentName
+            );
+            array_push($this->files["attachment"], $attachment);
+        } else {
+            $this->files["attachment"] = array(
+                array(
                     'filePath'   => $attachmentPath,
                     'remoteName' => $attachmentName
-                );
-                array_push($this->files["attachment"], $attachment);
-            } else {
-                $this->files["attachment"] = array(
-                    array(
-                        'filePath'   => $attachmentPath,
-                        'remoteName' => $attachmentName
-                    )
-                );
-            }
-
-            return true;
-        } else {
-            throw new InvalidParameter(INVALID_PARAMETER_ATTACHMENT);
+                )
+            );
         }
+
+        return true;
     }
 
     public function addInlineImage($inlineImagePath, $inlineImageName = null)
@@ -314,15 +310,7 @@ class MessageBuilder
 
     public function addCustomData($customName, $data)
     {
-        if (is_array($data)) {
-            $jsonArray                         = json_encode($data);
-            $this->message['v:' . $customName] = $jsonArray;
-
-            return $this->message['v:' . $customName];
-        } else {
-            throw new InvalidParameter(INVALID_PARAMETER_NON_ARRAY);
-        }
-
+        $this->message['v:' . $customName] = json_encode($data);
     }
 
     public function addCustomParameter($parameterName, $data)