DKIM, as explained by DKIM.org itself, lets organizations take responsibility for messages while in transit. "The organization is a handler of the message, either as its originator or as an intermediary," the site explains. "Their reputation is the basis for evaluating whether to trust the message for delivery. Technically DKIM provides a method for validating a domain name identity that is associated with a message through cryptographic authentication."

As the number of Google Apps users continues to grow (as the company pushes it heavily), this is a good feature for organizations to have to increase the deliverability of their messages. 

"Google has been an early and consistent supporter of email authentication technologies, which help ensure senders are who they say they are, and in turn help to curb spam," says Google Enterprise Product Manager Adam Dawes. "Since we launched Gmail in 2004, we have supported email-signing standards such as DomainKeys and DomainKeys Identified Mail (DKIM) to help validate outbound mail with digital signatures. On the inbound side, to help our users identify email from verified senders, in 2008 we worked with eBay and PayPal to authenticate their mail with DKIM and block all unsigned messages purportedly from those companies destined for Gmail users."

"But the spam and phishing epidemics aren’t letting up – every day Gmail filters out billions of unwanted messages from our users’ inboxes – so we’ve been focused on creating helpful tools and working with the email industry to bring solutions that will help our customers," continues Dawes. "Email authentication is an important mechanism to verify senders’ identities, giving users a tool to recognize potential spam messages. In addition, many mail systems can display whether a received message is DKIM-verified, which helps spam filters verify and assess the overall reputation of the sender’s domain: messages from untrusted senders are treated more skeptically than those from good senders."

With DKIM, Google Apps users’ messages are less likely to get caught in spam filters. The feature comes at no extra cost for customers too. 

This is only one of a variety of things Google has been doing lately with regards to email filtering. Last year, they introduced the Priority Inbox, which helps Gmail users filter through messages (even if those being filtered aren’t necessarily spam – legitimate messages, but deemed less important by users) and just this week, Google announced that Apps admins can create policies specifying who their users can communicate with over email. 

From time to time, news emerges on a company finding its usual email messages being treated as villainous rapscallions, denied entry to inboxes where they once arrived without incident. One day email’s traveling without incident, the next day it turns into O’Hare Airport on a snowy holiday weekend.

One’s email campaign doesn’t need to suffer from an unnecessary blockage (we mean this for legitimate opt-in marketers; you spammers deserve intestinal blockages along with your email being stuffed). We give credit to Mark Risher, group product manager for Yahoo Mail, for letting us know in an interview a mildly hidden benefit of DKIM.

Briefly, DKIM lets a mail server know an incoming message from a domain actually came from that domain. DKIM-capable mail servers check this and pass approved messages through.

Risher noted how in our piece about Google’s Gmail using DKIM to stop PayPal and eBay phishes, Google is knocking out a lot of incoming junk. As in more than a billion such messages per day.

Here’s why DKIM matters to legitimate email marketers. The technology authenticates a message as legitimately coming from the domain that sends it. The IP address for the domain may change; it’s not important to DKIM for authenticating email.

We think that’s a big selling point for anyone doing email marketing, one that hasn’t been emphasized enough. Instead of losing precious time reaching customers while making a change of hosting services and the relevant IP addresses, DKIM keeps the authentication in place and recipient servers happy.

Adoption continues apace throughout the Internet space, and Risher also said banking industry consortium BITS recommended adoption of DKIM for financial institutions. That would go a long way toward restoring trust in email messages from banks, a regularly spoofed item by criminal phishers.

Yahoo maintains a resource at postmaster.yahoo.com about contacting its domain with email. DKIM will help email marketers do so.