The Unicode community has identified suspicious combinations of letters that could be misleading, and Gmail will now begin rejecting email with such combinations. The Unicode Consortiums Highly Restricted specification strikes a healthy balance between legitimate uses of these new domains and those likely to be abused by spammers or scammers. Were rolling out the changes today, and hope that others across the industry will follow suit. Together we can help ensure that international domains continue to flourish, allowing both users and businesses to have a tte–tte in the language of their choosing.”]
Source: https://security.googleblog.com/2014/08/protecting-gmail-in-global-world.html