Google has added another weapon to its arsenal in the ongoing battle against spam by giving Google Apps users a simple way to digitally sign email and authenticate their identity. Today, Google (NASDAQ: GOOG) announced all Google Apps business customers will have the option of signing their messages with DomainKeys Identified Mail (DKIM) as a way to help validate the sender. Google said it's the first major email platform to offer DKIM at no extra cost and that includes on-premises providers.

"Today, we mark another notch in the spam-fighting belt: we’re making it possible for all Google Apps customers to sign their outgoing messages with DKIM, so their sent mail is less likely to get caught up in recipients’ spam filters," Adam Dawes, a Google Enterprise product manager, said in a blog post.

Google said there are over 3 million business customers of the cloud-based Google Apps suite. Google Apps administrators can enable DKIM sign-ins starting today in the Advanced Tools tab of the Google Apps control panel.


"As more email providers around the world support DKIM signing, spam fighters will have an even more reliable signal to separate unwanted mail from good mail," said Dawes. "We're pleased to let millions more organizations use DKIM with this improvement."

One early supporter of Google's announcement is email security provider eCert Systems.

"We help the most-phished brands on the Internet manage their mail authentication programs, and the Google Apps solution is the simplest that we've encountered," Kelly Wanser, CEO of eCert Systems, said in a statement. "Configuring DKIM for in-house systems requires plug-ins or additional gateway servers, making a company's mail environment more complex and difficult to manage. As a Google Apps customer, this feature took us only a few clicks in the control panel and an update of our DNS."

Google had earlier done some work on the inbound side to help its users identify email from verified senders. Back in 2008, Dawes said Google worked with eBay and PayPal to authenticate their mail with DKIM and block all unsigned messages purportedly from those companies destined for Gmail users. Google's Gmail service alone already filters out billions of unwanted messages from user's inboxes every day, the company said.

Ironically, Google's news come at a time when the volume of spam, while still enormous, dropped significantly in the second half of 2010. But security vendor Symantec predicted last month that 2011 will see a marked increase in language-targeted spam, particularly in Europe and Asia. In 2010, roughly 95 percent of all spam was in English, but that figure is expected to slip to around 90 percent in 2011 while Portuguese and Spanish spam will increase significantly.

David Needle is the West Coast bureau chief at InternetNews.com, the news service of Internet.com, the network for technology professionals.

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