diff --git a/README.md b/README.md
index 05e8e7d..85c71d4 100644
--- a/README.md
+++ b/README.md
@@ -14,8 +14,8 @@ Here are the currently supported services:
 * [Mailgun](http://www.mailgun.com) (complete)
 * [Postmark](https://postmarkapp.com) (complete)
 * [Postage](http://postageapp.com) (complete)
-* [Send Grid](http://sendgrid.com) (nearly complete)
-* [Spark Post](http://sparkpost.com) (nearly complete)
+* [SendGrid](http://sendgrid.com) (nearly complete)
+* [SparkPost](http://sparkpost.com) (nearly complete)
 * [Amazon SES](http://aws.amazon.com/ses) (nearly complete, attachments are missing)
 * [Mandrill](http://mandrill.com) (complete, but please don't use this party, as Mailchimp / Mandrill do not actively maintain this service)
 
diff --git a/src/Service/SparkPostService.php b/src/Service/SparkPostService.php
index 89f7eb5..7e85ef0 100644
--- a/src/Service/SparkPostService.php
+++ b/src/Service/SparkPostService.php
@@ -524,32 +524,27 @@ private function parseResponse(HttpResponse $response, array $successCodes = [])
             return $result;
         }
 
-        // There is a 4xx error
-        if ($response->isClientError()) {
-            if (isset($result['errors']) && is_array($result['errors'])) {
-                $message = implode(', ', array_map(
-                    function ($error) {
-                        return $error['message'];
-                    },
-                    $result['errors']
-                ));
-            } elseif (isset($result['error'])) {
-                $message = $result['error'];
-            } else {
-                $message = 'Unknown error';
-            }
-
-            throw new RuntimeException(
-                sprintf(
-                    'An error occurred on SparkPost (http code %s), messages: %s',
-                    $response->getStatusCode(),
-                    $message
-                )
-            );
+        if (isset($result['errors']) && is_array($result['errors'])) {
+            $message = implode(', ', array_map(
+                function ($error) {
+                    return $error['message'];
+                },
+                $result['errors']
+            ));
+        } elseif (isset($result['error'])) {
+            $message = $result['error'];
+        } else {
+            $message = 'Unknown error';
         }
 
-        // There is a 5xx error
-        throw new RuntimeException('SparkPost server error, please try again');
+        throw new RuntimeException(
+            sprintf(
+                'An error occurred on SparkPost (http code %s), messages: %s',
+                $response->getStatusCode(),
+                $message
+            ),
+            $response->getStatusCode()
+        );
     }
 
     public function previewTemplate(