Technically your email address isn't bob@[mailbox].kz, it's bob@xn--h78h.kz which your browser and possibly some mail clients will render as bob@[mailbox].kz. But xn--h78h@emojimail.com will always just display as xn--h78h@emojimail.com.

For the domain part, browsers and email providers have collectively agreed to render domains of the form xn-[stuff]-[stuff].[tld] according to the Punycode specification, but no such rendering exists for the username.