I just wonder how common such addresses are ? For testing purposes I tried to create one on a VPS I’m using, but it doesn’t accept such chars. Then I tried some freemail providers (Yahoo, live.com, web.de) - no chance.
There is a newer rfc that describes utf8 support, but there are probably still a lot of systems running built around the older rfcs that would not allow anything beyond basic ascii plus allowed symbols.
I have no idea if the current class supports utf8 for addresses, but if you can find a server that does you could always test it. My guess is that you won’t find many servers that support it yet. RFC 6530