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What is EAI (Email Internationalization)?

EAI (Email Address Internationalization) is the set of standards, chiefly RFC 6530 to RFC 6533, that allow email addresses to contain Unicode characters in both the part before the @ and the domain name. A sending server announces support with the SMTPUTF8 extension, and a receiver that does not advertise it must be sent an ASCII address instead. IDN (Internationalized Domain Names) covers only the domain half and predates EAI.

An EAI address

राम@डाटामेल.भारत

The domain half can also be written in ASCII as punycode (xn--...) and will resolve either way. The local part, राम, has no ASCII form: it exists only if both the sending and receiving servers support SMTPUTF8.

What breaks

Software written before EAI assumes an address is 7-bit ASCII. Typical failures in anti-spam products:

  • Rejecting the MAIL FROM as malformed, so legitimate mail from Indian, Arabic or Chinese-script domains bounces.
  • Failing to look up SPF or DMARC because the domain was not converted to punycode before the DNS query.
  • Mis-parsing headers with UTF-8 addresses and mis-scoring them as spam.
  • Logging and quarantine interfaces that display mojibake.

Why it matters in India

India’s own script domains under .भारत and the other Indian-language top-level domains, together with government initiatives to put email in local languages, mean EAI traffic is real inbound mail for ISPs and public-sector bodies, not an edge case.

EAI in Spamjadoo

Spamjadoo advertises SMTPUTF8, normalises domains to punycode before every DNS check, and applies the full handshake policy to EAI mail. See EAI-ready antispam for details.

Last reviewed 10 September 2026 by Spamjadoo engineering.