diff --git a/src/MessagePart.php b/src/MessagePart.php
index ce7b7ce..49493d4 100644
--- a/src/MessagePart.php
+++ b/src/MessagePart.php
@@ -99,11 +99,17 @@ public function getContentType(): string
 
     public function getContent(): string
     {
+        $content = $this->content;
+
         if (strtolower($this->getHeader('Content-Transfer-Encoding', '')) === 'base64') {
-            return Utils::normaliseLineEndings(base64_decode($this->content));
+            $content = base64_decode($content);
+        }
+
+        if ($this->isAttachment()) {
+            return $content;
         }
 
-        return Utils::normaliseLineEndings($this->content);
+        return Utils::normaliseLineEndings($content);
     }
 
     public function isHtml(): bool
@@ -123,16 +129,16 @@ public function isImage(): bool
 
     public function isAttachment(): bool
     {
-        return str_starts_with($this->getHeader('Content-Disposition', ''), 'attachment');
+        return str_starts_with(strtolower($this->getHeader('Content-Disposition', '')), 'attachment');
     }
 
     public function getFilename(): string
     {
-        if (preg_match('/filename=([^;]+)/', $this->getHeader('Content-Disposition'), $matches)) {
+        if (preg_match('/filename=([^;]+)/i', $this->getHeader('Content-Disposition'), $matches)) {
             return trim($matches[1], '"');
         }
 
-        if (preg_match('/name=([^;]+)/', $this->getContentType(), $matches)) {
+        if (preg_match('/name=([^;]+)/i', $this->getContentType(), $matches)) {
             return trim($matches[1], '"');
         }