The US National Institute of Standards and Technology, which is responsible for developing information security standards and guidelines for federal information systems, has published a draft revised guide on 'Trustworthy Email'. The document outlines several recommendations and guidelines for enhancing true in email, such as: the use of mechanisms for authenticating a sending domain, techniques for assuring email transmission security, and encryption and authentication of message content. The draft guide also contains a series of recommendations on techniques for reducing 'unsolicited bulk email' (spam): approved/non-approved sender lists, domain-based authentication techniques, content filtering, and user education.