I'm still curious about the question of whether an email from Berlin to Moscow goes through. Does anyone know?
An email from a major provider (gmail, etc) is much more likely (in many circumstances) to make it past spam blocks and other blocks than emails from "lesser" servers. An email from your ISP's mail host may be more or less or equally likely to make it through than one from a self-hosted mailserver, depending on how well those servers are set up (getting SPF, DKIM, DMARC, and the other such settings right can be difficult).
But when you are talking about emails crossing political borders that involve international tensions, there are likely a lot of other factors completely out of your control. Asking us to tell you whether it will get through or not is not necessarily helpful to you, as our experience in such matters may vary from yours. (Personally, I have not knowingly tried to email someone in Moscow, so I cannot give an anecdote, helpful or otherwise.)