Markus Siebold founded his first business directly after completing his Master's degree in 1993 (Marketing and Market Research at the university of Bayreuth). This involved selling airline tickets over the phone. This was his first experience with mail-order businesses.

When the internet became popular, he and his business partner founded one of the first internet travel agencies in Germany (Travelgate AG – together with Munich based Telegate AG).

During the massive downturn of the tourism industry after 9/11, he decided to set up his own e-commerce consultancy called Drei75 web-strategies. He has been successfully operating and generating business for Drei75 since then and is currently based in Düsseldorf. Through this, he sells his online expertise to the mail order industry. He also teaches at the International FH, Bad Honnef.

All of his strategic projects are usually accompanied by psychological market research. He shares the insights that his consultancy has gained with clients such as Otto, Sky, Hugo Boss, Gourmondo, Heine and Baur.