McAfee on Monday rolled out new integration and performance updates to its on-demand e-mail and Web protection applications and said that more than 575,000 customers are now using its suite of Software-as-a-Service (SaaS) security offerings.

The updates include enforced Transport Layer Security (TLS) features for inbound and outbound e-mail delivery for specific domains.

Also, McAfee (NYSE: MFE) is now offering a new downloadable Outlook 2003/2007 integration add-on, enabling message archive administrators to search, view, and save copies of archived messages directly through a Microsoft Outlook 2003 or 2007 e-mail client.

Finally, the enhancement versions now include additional language support for all services, including Chinese, Portuguese, Russian, Japanese, and Turkish.

While McAfee has offered cloud-based security applications for more than a decade, its $140 million acquisition of MX Logic last year really catapulted it to the top of the on-demand security software sector.

At the time the purchase was completed, MX Logic's on-demand offering was used by more than 4 million end-users at over 40,000 companies.

"With the industry's broadest portfolio of massively scalable and multi-tenant security solutions and our ability to let users choose between SaaS, on-premises or a combination of both, we simply believe that nobody can serve the dynamic security needs of customers better than McAfee," Marc Olesen, general manager of McAfee's Software-as-a-Service group, said in a statement.

"Along with the acquisition of MX Logic in July 2009, the customer milestone and new service releases demonstrate the commitment and enormous momentum McAfee has for its Security-as-a-Service business," he added.

This growth-through-acquisition strategy has become especially pronounced among would-be and established on-demand security vendors in the past year.

Both IBM (NYSE: IBM) and Symantec (NASDAQ: SYMC) have made steady investments in their on-demand units and Cisco Systems (NASDAQ: CSCO) made a serious splash in the sector with its $830 million purchase of Iron Port in 2007, giving it the ability to offer both on-site and cloud-based security options to large enterprise customers.

Market researcher Gartner predicts SaaS sales will more than double between now and 2012 to more than $13 billion, with security applications compromising an increasingly larger percentage of total on-demand sales for the foreseeable future.

"Initial concerns over security, response time, and service availability have diminished for many organizations as SaaS business and computing models have matured and adoption have become pervasive," Gartner analyst Sharon Mertz said in a research report released in October.

Larry Barrett is a senior editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.