Home / Blogs

Searching for Truth in DKIM: Part 3 of 5

J.D. Falk

Last year, MAAWG published a white paper titled Trust in Email Begins with Authentication [PDF], which explains that authentication (DKIM) is "[a] safe means of identifying a participant-such as an author or an operator of an email service" while reputation is a "means of assessing their trustworthiness."

Reputation systems based on IP addresses, including Return Path's Sender Score, are used by many ISPs and anti-spam vendors to determine which mail to accept, which to reject, and which to subject to additional filtering before making a delivery decision. There, the identifier is the IP address.

The reason this sort of reputation works for delivery decisions is that it's an attempt to predict whether the sender of a message can be trusted to send mail that the recipients want — or, more accurately, whether the IP address of a message can be trusted to send mail that the recipients won't complain about. We also mix in the concept of safety, largely in the form of how likely it is that the IP address is sending phishing scams or similar bad stuff.

In part 1 of this series, we described how the DKIM "d=" identifier brings us closer to knowing who sent a message, because it can be tied to the company or person who registered that domain name.

Reputation or certification based on the DKIM d= identifier will have the same goal — and will be more effective, because it will be tied to the signing entity rather than a single IP address. When ADSP is applied, that signing entity could be the author domain (see part 2). If not, it's still a useful method for determining whether to trust the message. Any d= domain who regularly signs trusted messages becomes trustworthy, and vice versa.

Plus, d= reputation is portable — the owner of the d= domain can use that same identifier on multiple IP addresses, even bringing it to a different ESP (as we described in part 2), without having to start over from scratch or to "warm up" IPs.

While not absolutely perfect, reputation and certification based on d= will be far more accurate, effective, and convenient than when it's based solely on the IP address. But, does a trustworthy d= domain indicate a truthful message? Stay tuned for part 4.

(This article was originally published by Return Path)

By J.D. Falk, Internet Standards and Governance. More blog posts from J.D. Falk can also be read here.

Related topics: Domain Names, Email, Security, Spam

WEEKLY WRAP — Get CircleID's Weekly Summary Report by Email:

Comments

To post comments, please login or create an account.

Related Blogs

Related News

Topics

Industry Updates – Sponsored Posts

General Availability Period for New .RED Top-Level Domain Opens

General Availability Period for New .BLUE Top-Level Domain Opens

General Availability Period for New .PINK Top-Level Domain Opens

New Chinese "Mobile" Top-Level Domain Now Available

New .KIM Domain Goes Live

Welcome .SHIKSHA! General Availability Now Open

Adrian Kinderis Appointed as Chair of Domain Name Association

Internet Reaches 271 Million Domain Names in the Fourth Quarter of 2013

The Future of Chinese Domain Names (a Panel Discussion)

dotStrategy Selects Neustar's Registry Threat Mitigation Services for .BUZZ Registry

Tony Kirsch Announced As Head of Global Consulting of ARI Registry Services

24 Million Home Routers Expose ISPs to Massive DNS-Based DDoS Attacks

Afilias Chairman Appointed to Domain Name Association Board

.BUILD Enters Landrush with Support of ARI Registry Services

Radix Awards Contracts for .website, .host, .space, and .press to CentralNic plc

Afilias Welcomes "Dot Chinese Online" and "Dot Chinese Website" Top-Level Domains to the Internet

What Does a DDoS Attack Look Like? (Watch First 3 Minutes of an Actual Attack)

Joining Forces to Advance Protection Against Growing Diversity of DDoS Attacks

Afilias Welcomes .ONL and .RICH to the Internet

Why Managed DNS Means Secure DNS

Sponsored Topics