Tesla Inc. has been effectively blocked from delivering new cars to its customers in Sweden after the electric vehicle maker lost an appeal against the country’s postal service.

The legal ruling against Elon Musk’s company means it cannot receive license plates intended for new EVs, making it difficult for customers in its fifth biggest European market to legally drive Teslas on the roads. Postal workers in Sweden are refusing to handle any Tesla-related mail in sympathy with a walkout by repair-shop mechanics that began Oct. 27.