Great companies start with an awesome team
OX Leadership Team
At Open-Xchange, leadership is more a mindset than a title. The nature of our organization is geared towards a flat hierarchy and an open way of working together. The leadership team supports this approach through a mix of business expertise, entrepreneurial experience and operational know-how. Our culture encourages an open approach – exploring, experimenting and mixing things up. You can see the results everywhere – in our people, in our partners and how we develop multi-cultural teams.
OX Supervisory Board
Richard Seibt
Chairman of the Supervisory Board
Since 1978 Richard Seibt profits from a long experience in the IT business and has served as Chairman of the Open-Xchange Supervisory Board, apart from a short break in 2021, since December 2006. As Managing Director at IBM Germany, he handled software sales and marketing in Germany, Austria, Switzerland and Eastern Europe. He then worked as VP Software Sales and Marketing North America and as General Manager for a worldwide operating system software Division. In 1998, he became an Executive Management board member at United Internet. In 2003, Seibt was appointed CEO at SuSE Linux and in 2004 (following the company’s acquisition by Novell), he became President of Novell EMEA (Europe, Middle East and Africa). Since leaving Novell in 2005, he has been working as a business angel and board member for several other international software companies.
Achim Weiß
Achim Weiß is the CEO of IONOS, where he is responsible for the company's overall strategy and product development. Weiß has more than 20 years of experience in the European internet industry and in 1995 co-founded Schlund + Partner, the German web hosting pioneer that was taken over by 1&1 in 1998. As Chief Technology Officer at 1&1 until 2008, Weiß developed, amongst other things, the world's first web hosting platform for the rapidly growing mass market. As one of the leading experts in the field of developing scalable internet infrastructures, Weiß founded ProfitBricks, the first German cloud infrastructure solutions (IaaS) provider in 2010. After 1&1 acquired ProfitBricks in 2017, he returned to the board and was appointed CEO of IONOS in October 2018.
Serguei Beloussov
Serguei Beloussov is a serial entrepreneur, the founder of the Schaffhausen Institute of Technology (SIT), Acronis, Parallels, Acumatica, Runa Capital and other technology companies. Serguei has over 20 years of experience building, leading, and growing high-performing, multi-national high-tech companies. Presently, he is focused on developing innovative cyber protection technology as the Chief Research Officer at Acronis and developing SIT campuses in Schaffhausen and Bremen.
Curt Gunsenheimer
Curt Gunsenheimer, Senior Partner at Iris Capital, joined the company in 2002. He is responsible for investments in late-stage and growth capital across Europe and supports companies across Germany and France in stages of global expansion. Gunsenheimer has twenty years of experience in venture capital and public-market financing of growth technology companies, with particular expertise in the field of software. Prior to joining Iris Capital, he worked at Goldman Sachs and Robertson Stephens.
Dr. Paul-Josef Patt
Dr. Paul-Josef Patt is CEO of eCAPITAL entrepreneurial Partners, a German venture capital company. He has worked as a Project Manager at Roland Berger & Partner, the leading German strategy consultancy and as Director of Corporate Strategy at Kaufhof Holding, managing the expansion of one of Germany’s biggest retailers. After his successful exit, Patt started working as a business angel and venture capitalist. He took over the lead at eCAPITAL in 2004 and has overseen the company’s impressive growth. He has a strong track record in financing and developing young high-tech companies and as lead investor, initiated the sale of Novaled to Samsung in 2013 – at that time, the largest venture capital deal in the German hi-tech sector. Patt serves on several boards, including sonnen, Jedox AG and Heliatek.


Andreas Gauger
Chief Executive Officer
OX's CEO Andreas Gauger has been heavily involved in shaping the cloud and...


Frank Hoberg
Chief Sales Officer
Hoberg co-founded Open-Xchange together with Rafael Laguna (now Director SprinD...


Stephan Martin
EVP Services
Over the past 10 years, Martin has built Open-Xchange’s professional services...


Dirk Valbert
Chief Financial Officer


Stefan Preuss
SVP Project Delivery
Preuss leads the project delivery department and engineering for all OX Cloud...


Matthias Biggeleben


Timo Sirainen
Creator & Chief Architect, Dovecot OY
Sirainen programmed the Dovecot IMAP Server in 2002, releasing the first...


Bob Brandt
VP, PowerDNS Engineering, PowerDNS
Brandt manages the PowerDNS Engineering team and is ultimately responsible for...

Andreas Gauger
Chief Executive Officer
OX's CEO Andreas Gauger has been heavily involved in shaping the cloud and hosting market in Germany since the 1990s.
He founded his first software company when he was still at school and, in 1995, was co-founder of the German hosting pioneer Schlund+Partner. From 2000 to 2008, as the board spokesperson, Gauger drove forward the growth of 1&1 to become both the European market leader in hosting and a leading German ISP and telecommunications provider.
In 2010, he co-founded the internationally successful cloud provider ProfitBricks, of which he was CEO until 2016. Since then, he has been supporting investment companies as a consultant in the SaaS environment.

Frank Hoberg
Chief Sales Officer
Hoberg co-founded Open-Xchange together with Rafael Laguna (now Director SprinD) in 2005 and serves as Chief Sales Officer, leading OX´s worldwide sales organization where he is taking care of major customer and distribution partnerships, and business development.
Hoberg served as OX CEO from 2004 – 2008, establishing partnerships with 1&1, the leading web hosting company in Europe and other major customers. He co-founded Netline Internet Service, the predecessor to Open-Xchange, in 1998 with Martin Kauss. In his role as Netline’s CEO, he was crucial in establishing the key partnership with SUSE Linux.

Stephan Martin
EVP Services
Over the past 10 years, Martin has built Open-Xchange’s professional services team from scratch, creating the global services structure for the full customer lifecycle from presales to support. Spread across 8 countries and counting, his teams are responsible for working with customers to customize their unique software architecture designs, sizings and integrations.
Before joining Open-Xchange, Martin was a senior consultant for SUSE Linux in the email and security services group. He was also part of a small team dedicated to sales and architecture support for Novell’s top EMEA Linux customers.

Dirk Valbert
Chief Financial Officer

Stefan Preuss
SVP Project Delivery
Preuss leads the project delivery department and engineering for all OX Cloud platform related products at Open-Xchange.
His Project Delivery Team consists of Professional Services and Engineering Services and is responsible for managing and executing large scale projects, deployments, and migrations for the entire OX product portfolio. Together with his teams, Preuss supports OX’s entire On- Prem and OX Cloud customer base. Related to this, he is responsible for engineering for OX Cloud platform related product components and the OX migration frameworks.
Preuss joined OX in 2000 as one of the first employees and has held various management roles in Engineering and Services. Over the last two decades he has played a critical role in developing and maintaining key products, including OX5 and OX6, OX App Suite and solutions based on OX Cloud.
He also built the Engineering Services Team, which has software engineers located all over the world, and provides software solutions spanning individual customer integrations and customization to OX Cloud, through to specific core components and migrations. In 2018 he took over responsibility for parts of the Services Teams to help streamline project delivery.

Matthias Biggeleben

Timo Sirainen
Creator & Chief Architect, Dovecot OY
Sirainen programmed the Dovecot IMAP Server in 2002, releasing the first version later that year. In 2011, he co-founded Dovecot OY to provide professional support and consultation services for the Dovecot software family. Under his stewardship, Dovecot has grown to over 3.5 million IMAP server installations – a global market share of almost 70%.
Sirainen has worked as a software developer for Directi in India, Rackspace in Virginia and Portugal Telecom. In 2015, Dovecot merged with Open-Xchange to create one of the largest open-source companies in Europe capable of offering complete, end-to-end software and security solutions for service providers.

Bob Brandt
VP, PowerDNS Engineering, PowerDNS
Brandt manages the PowerDNS Engineering team and is ultimately responsible for Open-Xchange's suite of PowerDNS products. A Dutchman, born in Scotland, he has a lifetime of international experience, living in multiple countries and working for various international clients during his career as a cybersecurity professional.
Before joining Open-Xchange, Brandt worked for KPN Security, managing the teams providing Managed-Security Services to KPN's commercial customers. He previously worked in product and project management roles for companies including Netscout and Fox-IT.