This gets asked every time Yandex mail is mentioned. Nobody can answer this question. We can just speculate that Russia is evil and wants to read your emails. Just like Yahoo which scans and analyzes your emails apparently for NSA or Google which scans your emails for ads. Seems to me like privacy is a concern as long as your email isn't on your own server.
I agree with sakapov(sp?), it's not an answer we can really know, but I think it's safe to say most every large government is very very happy to read every email they can get their hands on. But think of it a different way, if A government is going to read your email(and it's pretty safe to say they will), then who would you rather read it, one you are beholden to, or one that probably doesn't care at all about you, since you are not their citizen, and are not doing anything against them?
Hence, why I use Yandex. As an American, what do I care if Russia reads my email?