diff --git a/snappymail/v/0.0.0/app/libraries/MailSo/Mime/Enumerations/ContentType.php b/snappymail/v/0.0.0/app/libraries/MailSo/Mime/Enumerations/ContentType.php
index dacc39637..f6761dd45 100644
--- a/snappymail/v/0.0.0/app/libraries/MailSo/Mime/Enumerations/ContentType.php
+++ b/snappymail/v/0.0.0/app/libraries/MailSo/Mime/Enumerations/ContentType.php
@@ -24,6 +24,8 @@ abstract class ContentType
 	const PGP_SIGNATURE = 'application/pgp-signature';
 	const PKCS7_SIGNATURE = 'application/pkcs7-signature';
 	const PKCS7_MIME = 'application/pkcs7-mime';
+	// RFC 3462
+	const REPORT = 'multipart/report'; // ; report-type=delivery-status;
 
 	public static function isPkcs7Mime(string $data) : bool
 	{
diff --git a/snappymail/v/0.0.0/app/libraries/snappymail/file/mimetype.php b/snappymail/v/0.0.0/app/libraries/snappymail/file/mimetype.php
index 62f186737..6156145da 100644
--- a/snappymail/v/0.0.0/app/libraries/snappymail/file/mimetype.php
+++ b/snappymail/v/0.0.0/app/libraries/snappymail/file/mimetype.php
@@ -226,6 +226,10 @@ abstract class MimeType
 
 		'eml' => 'message/rfc822',
 		'mime' => 'message/rfc822',
+		// RFC 3464
+//		'u8dsn' => 'message/delivery-status',
+		// RFC 5337
+		'u8dsn' => 'message/global-delivery-status',
 
 		'txt' => 'text/plain',
 		'asp' => 'text/asp',