Subject: Base64-encoded message/rfc822 attachment
From: [email-masked]
To: [email-masked]

Outer body.
U3ViamVjdDogSGkKRnJvbTogYWxpY2VAbWltZS50ZXN0LmludmFsaWQKVG86IGJvYkBtaW1lLnRlc3QuaW52YWxpZApNZXNzYWdlLUlEOiA8aW5uZXIubXNnLjMzMzg4MEB0ZXN0LmludmFsaWQ+CkNvbnRlbnQtVHlwZTogdGV4dC9wbGFpbjsgY2hhcnNldD11dGYtOAoKSGVsbG8uCg==