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In my answer here, I was explaining about Internationalized country code top-level domains. Unfortunately, standard links for some reason do not allow users to click on such links.
Such addresses are valid, so I believe that this is a bug which needs to be fixed.
Link to question on SO meta here.
Related SO meta question here.
If you add the links via the Insert Hyperlink option present on the toolbar, the links will be converted to punycode & URL encoded.