Amazon is continuing to expand its cloud empire into more parts of the enterprise with a new email service geared specifically toward knowledge workers. The launch matches its two biggest rivals on an important office productivity front as the competition shifts beyond pricing to functionality.

The retail-turned-cloud-giant has never had any trouble keeping up with the pace of change. On top of making 50 rounds of price cuts since launching its infrastructure-as-a-service business in 2006, Amazon also rolls out hundreds of updates every year, many of which introduce entirely services that don’t have equivalents elsewhere.

But when it comes to business applications, the competition has the upper hand. Microsoft continues to dominate corporate email and calendering thanks to its head start in on-premise environments while Google is seeing its online productivity suite, which encompasses Gmail, gain traction with organizations the world over.

That apparently doesn’t faze Amazon, however, which is aiming its new WorkMail offering directly at enterprise customers, particularly those with global operations. Along with standard features such as a company-wide address book and shared calenders, the service also boasts an emphasis on security that should appeal to decision-makers in this day of seemingly rampant corporate data breaches.

Messages sent through WorkMail are automatically encrypted using Amazon’s key management service, with the option of using a customer organization’s own ciphers for added control, and only decrypted upon arriving at their destinations. Amazon also offers customers the option of storing mail only in geographically designated areas, a feature that should appeal to companies in highly regulated European markets. The service also provides integration with existing email clients and user directories, two segments that are dominated by rival Microsoft.

Amazon hopes that that integration will make it easier for organizations to migrate from their existing deployments onto its cloud, which not only offers email capabilities but a native directory to replace in-house implementations as well. The company has also hooked up its Zocalo file-sharing service to WorkMail to enable users to exchange files easily by email.

The same functionality and more is available in the cloud-based productivity suites from Google and Microsoft, but as the launch highlights, the retail giant is quickly narrowing the gaps. If Amazon’s breakneck advance on the infrastructure-as-a-service front is any indication, the two web giants could soon have a formidable competitor on their hands in the enterprise productivity space.