That’s certainly not true in all cases. I correspond regularly with a Russian friend who uses a Russian email server, and her messages have not been sent to my spam folder.

OTOH, for years I have gotten emails from someone (or thing) that speaks Polish. I’ve never taken the trouble to translate them because their liberal use of emoticons tells me they’re spam, so from the very first I marked them for the spam folder. And while I see more like them every time I take a gander in the sewer, new stuff in Polish still keeps showing up every now and then in my inbox.