diff --git a/src/Adapter/Mailjet/MailjetAdapter.php b/src/Adapter/Mailjet/MailjetAdapter.php
index 49b9a17..7b25c07 100644
--- a/src/Adapter/Mailjet/MailjetAdapter.php
+++ b/src/Adapter/Mailjet/MailjetAdapter.php
@@ -202,6 +202,18 @@ private function createMessage(MessageInterface $message)
             if ($message->hasVariables()) {
                 $m['Variables'] = $message->getVariables();
             }
+
+            if ($message->hasAttachments()) {
+                $m['Attachments'] = [];
+
+                foreach ($message->getAttachments() as $attachment) {
+                    $m['Attachments'][] = [
+                        'ContentType' => $attachment->getType(),
+                        'Filename' => $attachment->getName(),
+                        'Base64Content' => $attachment->getData(),
+                    ];
+                }
+            }
         } else {
             $m['HTMLPart'] = $message->getHtml();
             $m['TextPart'] = $message->getText();
diff --git a/src/Adapter/SparkPost/SparkPostAdapter.php b/src/Adapter/SparkPost/SparkPostAdapter.php
index e1973eb..3ba2bcf 100644
--- a/src/Adapter/SparkPost/SparkPostAdapter.php
+++ b/src/Adapter/SparkPost/SparkPostAdapter.php
@@ -99,6 +99,18 @@ public function sendMail(MessageInterface $message)
             if ($message->hasSubstitutionData()) {
                 $payload['substitution_data'] = $message->getSubstitutionData();
             }
+
+            if ($message->hasAttachments()) {
+                $payload['attachments'] = [];
+
+                foreach ($message->getAttachments() as $attachment) {
+                    $payload['attachments'][] = [
+                        'type' => $attachment->getType(),
+                        'name' => $attachment->getName(),
+                        'data' => $attachment->getData(),
+                    ];
+                }
+            }
         } else {
             $payload['content']['html'] = $message->getHtml();
             $payload['content']['text'] = $message->getText();
diff --git a/src/Model/Attachment/Attachment.php b/src/Model/Attachment/Attachment.php
index fd6e7ed..13a285f 100644
--- a/src/Model/Attachment/Attachment.php
+++ b/src/Model/Attachment/Attachment.php
@@ -12,12 +12,12 @@ class Attachment implements AttachmentInterface
     /**
      * @var string
      */
-    protected $name = '';
+    protected $name = 'Attachment';
 
     /**
      * @var string
      */
-    protected $type = '';
+    protected $type = 'application/octet-stream';
 
     /**
      * @var string
@@ -33,11 +33,12 @@ public function getName()
     }
 
     /**
+     * Name of file.
      * @param string $name
      */
     public function setName($name)
     {
-        $this->name = $name;
+        $this->name = (string)$name;
     }
 
     /**
@@ -49,11 +50,12 @@ public function getType()
     }
 
     /**
+     * MIME type of file.
      * @param string $type
      */
     public function setType($type)
     {
-        $this->type = $type;
+        $this->type = (string)$type;
     }
 
     /**
@@ -65,10 +67,11 @@ public function getData()
     }
 
     /**
+     * Base64 encoded file content.
      * @param string $data
      */
     public function setData($data)
     {
-        $this->data = $data;
+        $this->data = (string)$data;
     }
 }