diff --git a/testdata/attachment b/testdata/attachment
new file mode 100644
index 0000000..fc21731
--- /dev/null
+++ b/testdata/attachment
@@ -0,0 +1 @@
+This is a test attachment
diff --git a/testdata/attachment.license b/testdata/attachment.license
new file mode 100644
index 0000000..615ea2b
--- /dev/null
+++ b/testdata/attachment.license
@@ -0,0 +1,3 @@
+// SPDX-FileCopyrightText: Copyright (c) 2022-2024 The go-mail Authors
+//
+// SPDX-License-Identifier: MIT