Can a non-English email sent from GMail be read on any non-Gmail recipient domain? For example, can email in Hindi sent from GMail be read by to Yahoo or Hotmail or rediffmail recipient?
it should work unless there are complicated filters set and somehow goes to spam or deleted?
The answer is a qualified yes. Google has very good support for other languages using the proper internet standards for the purpose. Some other mail systems do the same, and they'll display the mail just fine, while others are less compatible and may have a problem.
In my own experience, I exchange emails regularly in a number of writing systems (including various European languages, Hebrew and Arabic, but not Hindi) and 99% of the time I have no trouble at all either at my end or the correspondent's end. Still, it's impossible to guarantee success without trying a specific combination. One thing you could do is create accounts for yourself in those email systems and send some messages back and forth, and you'll find out soon enough how well they work!