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An internationalized domain name (IDN) is a domain name that contains non-ASCII characters — Arabic, Chinese, Cyrillic, accented Latin letters, and so on. Because DNS only supports ASCII characters, IDNs are encoded using Punycode, which converts Unicode characters into an ASCII-compatible form. Punycode-encoded domain labels begin with the prefix xn--. For example:
Unicode (U-label)Punycode (A-label)
münchen.dexn--mnchen-3ya.de
例え.jpxn--r8jz45g.jp
почта.рфxn--80a1acny.xn--p1ai
MailChannels Inbound Filtering supports both second-level IDNs and internationalized top-level domains (TLDs).

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How MailChannels handles IDNs

When you add an IDN, MailChannels automatically registers both its Unicode (U-label) form and its Punycode (A-label) equivalent. This ensures mail is filtered correctly regardless of which form a sending server presents. Email authentication checks (including SPF) convert U-labels to A-labels before performing DNS lookups, so records published under Punycode domain names are evaluated correctly. MX record verification in the Domain Console applies the same conversion.

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Add an IDN

Add an IDN the same way you add any domain — single entry or CSV bulk upload in the Host Console, or via the Provisioning API. See domain management for the full steps. You can enter the domain in either its Unicode form (münchen.de) or its Punycode form (xn--mnchen-3ya.de). MailChannels handles both.
If you use the cPanel/WHM plugin to provision domains, IDN domains are supported and can be added directly through the plugin.

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IDNs and domain aliases

If you add an IDN as a domain alias, MailChannels automatically creates a second alias for the Punycode equivalent. Deleting the Unicode alias also removes the Punycode alias. You do not need to manage both manually.

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Convert between Unicode and Punycode

Use a tool like punycoder.com to convert between the Unicode and Punycode forms of a domain.