I am currently reading a biography of the German mathematician Gerhard Gentzen and I have noticed that some, but not all, of his letters are signed off with a variation on "Heil Hitler."
How common a practice was this and did it have special significance compared to other ways of ending a letter?
Related to that, did people (such as soldiers) automatically respond to "Heil Hitler" by repeating the phrase while saluting? I've seen it a few times in movies and tv shows, and was wondering if that was actually practiced.
It was expected and became common practice to end letters with "Heil Hitler" or with the phrase "mit deutschem Gruß" (with German greetings). All official administrative correspondence used "Heil Hitler" and it was the norm among supporters of the Nazi party. Omitting could already be considered a subtle form of resistance, especially if in response to a document which included the phrase.
I can't cite a specific source off the top of my head, the above is based on my research work in German archives. What struck me, was that often the "Heil Hitler" at the end of letters came across almost as comical, when the document in question was extremely mundane, like a report about overflowing sewage pipes...
Related question....was there a 'Heil Deutschland' or equivalent used?