"Lieber Gustav, auch die besten Grüße senden wir Dir wie geht es Dir? Dein Cosens Franz Püschel, August Püschel, Karl Püschel nebst Tante. schreib Du auch mal."

My friend Diedrich suggests this translates as: "Dear Gustav, Also the best greetings we send you. How are you? Your cousins Franz Püschel, August Püschel, Karl Püschel together with aunt. Do write (to us) too."
 The addressee would have been Heinrich August Gustav Lindner, 1862-1946, who came to the United States in 1885 and was followed here by his parents, Emil Heinrich Max Lindner and Christiane Charlotte Püschel. He was the uncle of Richard Otto Lindner