Email Filtering Best Practices Guide Version 1.0

Abstract: Provide best practices for filtering email messages in boundary protection devices (BPD), including commercial mail gateways, email attachment preprocessors or sidecars, and trusted guard (e.g., cross domain solution (CDS)) components.  The guidance in this document is based on over ten years of experience at NSA in developing and testing email BPD's.  This experience has provided valuable insight into how email filtering should be implemented in boundary protection devices.  This document is a supplement to “Inspection and Sanitization Guidance for Simple Mail Transfer Protocol (SMTP), Internet Message Format (IMF), and Multipurpose Internet Mail Extensions (MIME).”

Date Published:

Last Reviewed: 11 December 2017

Identifier: U/OO/234027-17

Dissemination Control: N/A

Length: 38 page(s)

Format: pdf

Type: Reference/Overview; Report

Tags: National Security Agency - NSA; Cyber; Guidance; Exploitation; Vulnerability; Data