In Central and Eastern Europe, as World War Two approached, there were many people trying to stay in touch with family members in foreign countries - or to find ways of getting to those countries themselves. Jews were the most obvious and largest group writing abroad or being written to. If you had a chance to write, then you wrote, and if people wrote to you - that was great news in itself!
Here is a cover sent from what I read as WIEN 8, 29 8 39 - less than a week before the German invasion of Poland - franked to 25 Pf. with Hindenburg rather than Hitler adhesives. It's sent to two people with what I take to be a Jewish name [ ... but can someone explain why the name is written as "Bibersteni" and not "Biberstein" ?] living in Jerusalem, then in British Mandate Palestine. The letter arrived - this is shown by the standard British censor tape. Interestingly, there is no sign of Censorship in Vienna. Nor is there any indication of the route taken by this letter (Click on Image to Magnify):