Open-Xchange received funds worth US$20 million from United Internet, Hermann-Josef Lamberti, and existing shareholders. A portion of the proceeds will fund a secondary transaction.

This latest round was the first new funding of Open-Xchange since 2008. That year the company raised US$9 million through a Series B round.

Open-Xchange was a maker of "Web-based communication, collaboration and office productivity open-source software." The company was a pioneer of the software-as-a-service (SaaS) product delivery. Now, the company wanted to make the most out of the cloud office systems shift.

"Open-Xchange has the potential to disrupt the cloud market in the coming years. Its technology will change how businesses and private users will buy and consume cloud services. Open-Xchange is uniquely positioned in this market, enabling telcos, web hosters, mobile and cable operators alike to successfully compete with over-the-top giants like Apple, Amazon, Facebook, Google and Microsoft," Lamberti said in a statement. Lamberti was recently added to the company's advisory board along with Dr. Oliver Mauss, who was the CEO of United Internet Ventures, a subsidiary of United Internet.