Dommermuth was born in 1963 and raised as the son of a realtor in
Montabaur, Germany. He has one brother. After initial training at the
Deutsche Bank, he started to work as a sales freelancer for a local PC dealer in his hometown Montabaur in 1983. In 1988, Dommermuth founded the 1&1 EDV Marketing GmbH together with a business partner. The first business idea was called "Software Börse", a marketing tool for software companies. For this product the company won the German direct marketing prize in 1989. The Company also organized special exhibitions at the
CEBIT in
Hannover, such as the "Software-Zentrum Mittelstand" and "Software for Europe." In 1992, his company 1&1 was commissioned by
Deutsche Telekom to sell
Bildschirmtext-access-points and later
T-Online accounts. In March 1998, the company had its
IPO as the first German Internet company. Due to the capital increase carried out in this context, 1&1 had opportunity to participate in other IT companies such as
GMX and Schlund + Partner AG. At the height of the
internet boom in the early 2000s, 1&1 Holding held shares in 17 internet companies and Dommermuth renamed the company to United Internet. Dommermuth owns 42% of United Internet, the Germany-headquartered broadband provider, which manages brands such as 1&1, GMX and Web.de, with 2020 turnover of Euro 5.4 billion, and 66 million accounts in 17 countries. From August 2014 to June 2015, he was a member of the
Supervisory Board of United Internet's investment
Rocket Internet. In summer 2017, United Internet contributed its subsidiary 1&1 Telecommunication SE to Drillisch AG and received new Drillisch shares in return. In total, United Internet owns over 75% of the renamed 1&1 Drillisch AG in January 2018. On 1 January 2018, Dommermuth also took over as Chairman of the Management Board of this company, which was renamed again in 2021 and now operates as
1&1 AG. 1&1 AG successfully participated in the 5G frequency auction of the German
Federal Network Agency in 2019. Dommermuth thus laid the foundation for the construction of a fourth mobile network in Germany. In August 2021, the company announced its intention to build Europe's most innovative mobile network based on the new OpenRAN technology together with the Japanese tech group Rakuten. Construction of the mobile network is scheduled to start in the same year. 1&1 will be Borussia Dortmund's shirt sponsor at Bundesliga matches from the 2020/21 season. For all international competitions, the DFB Cup and test matches abroad, the previous shirt sponsor
Evonik Industries would remain on the jerseys. Evonik Industries then sold just under 5 percent of its shares in Borussia Dortmund GmbH & Co. KGaA and reduced its stake to 9.8 percent. Dommermuth acquired a 5.0 percent stake in Borussia Dortmund through his Ralph Dommermuth Beteiligungen GmbH in early March 2020. Dommermuth is Germany's sole Internet billionaire, and the country's youngest self-made billionaire. ==Donations==