Yes, it's definitely German, although it was written by a non-native speaker or by someone who knew only dialectal German. I'm awful at reading the old German handwriting, so you'd better wait for someone else to tell you all the details. Basically, it's a postcard to someone called Hari [?], which was written by his mother. She says that she has sent him many letters, but hasn't heard from him in a long time. Her own husband died five months ago. She is very worried and sad and begs her son to write her a letter immediately to let her know that all is well with him and with his family.
PS: Out of curiosity - was her native language Yiddish, by any chance? The frequent double negatives and the unusual placement of the verbs might point that way.
Edit:
Okay, I gave it a try after all. But, as I said, I'm unsure about a lot of things and would be grateful for any corrections.

January 5th
Dear Hari,
I'm very surprised that I haven't received a letter from you, because I've sent you so many letters and haven't received an answer. For now it has been five months already that Papa died and I haven't received a letter from you yet. Has anything happened to you? [?]. Write me at once if you are all in good health and what the children are doing and what ... is doing, is she in good health? For Hari, I beg you to write me at once for my heart is sad enough as it is and I am worried about you and my eyes do not dry for crying. But then write me everything, if you are in good health, for all of us are in good health. Only I want to know about you, for I have only now received a letter from Klahra [?Klara?] that was written six months ago.
Many greetings to you and give everybody my greetings,
Your mother.