Mai won his first international medal at the 1985 European Athletics Indoor Championships, where he cleared 17.14 m to take the bronze medal. He then secured a triple jump and long jump double at the 1985 European Athletics Junior Championships held in Cottbus. That same year he ranked second in the triple jump at the 1985 European Cup. The following year he managed seventh at the 1986 European Athletics Championships. Another indoor medal followed at the 1989 European Athletics Indoor Championships and he was the silver medallist behind Nikolay Musiyenko of the USSR. His final appearance for East Germany came at the 1990 European Athletics Championships and he finished fifth behind his compatriot Jörg Friess.