The right-wing party is, in particular, opposed to the growing number of Muslims entering the country.
"We do not oppose Islam as a religion. However, it does not belong to Germany, but rather to those countries that have been influenced by Islam for centuries. A mosque is just another sign of Germany's increasing alienation," a statement on the party's official website said.
According to Dr. Dietrich Schönwitz, a city councilor from SPD, the construction of the mosque is just a pretext for the right-wing activists.
The city councils are now considering whether they should somehow react to the email campaign. Schönwitz believes, however, that the response should be well thought-out and cautious.
"I'm a bit reserved because I believe they're just trying to figure out how far they can go. When a court complaint fails, they will receive what they want, namely, attention. Nevertheless, the mayor has submitted a request to the public prosecutor to examine whether a complaint could lead to a success. Let's see what they say," the politician said.
In April 2016, "Der III. Weg" had already sent identical flyers to several politicians in the Berlin-Brandenburg area. Members of the Green party responded to the postcards with a humorous letter, saying that they would be happy to make a cruise along Africa's west coast if "Der III. Weg" will bear all the costs for the trip.