3. Problem Statement

Internationalizing Domain Names in Applications (IDNA) [RFC5890] permits internationalized domain names, but deployment has not yet reached most users. One of the reasons for this is that we do not yet have fully internationalized naming schemes. Domain names are just one of the various names and identifiers that are required to be internationalized. In many contexts, until more of those identifiers are internationalized, internationalized domain names alone have little value.

Email addresses are prime examples of why it is not good enough to just internationalize the domain name. As most observers have learned from experience, users strongly prefer email addresses that resemble names or initials to those involving seemingly meaningless strings of letters or numbers. Unless the entire email address can use familiar characters and formats, users will perceive email as being culturally unfriendly. If the names and initials used in email addresses can be expressed in the native languages and writing systems of the users, the Internet will be perceived as more natural, especially by those whose native language is not written in a subset of a Roman-derived script.

Internationalization of email addresses is not merely a matter of changing the SMTP envelope; or of modifying the "From:", "To:", and "Cc:" header fields; or of permitting upgraded Mail User Agents (MUAs) to decode a special coding and respond by displaying local characters. To be perceived as usable, the addresses must be internationalized and handled consistently in all of the contexts in which they occur. This requirement has far-reaching implications: collections of patches and workarounds are not adequate. Even if they were adequate, a workaround-based approach may result in an assortment of implementations with different sets of patches and workarounds having been applied with consequent user confusion about what is actually usable and supported. Instead, we need to build a fully internationalized email environment, focusing on permitting efficient communication among those who share a language and writing system. That, in turn, implies changes to the mail header environment to permit those header fields that are appropriately internationalized to utilize the full range of Unicode characters, an SMTP extension to permit UTF-8 [RFC3629] [RFC5198] mail addressing and delivery of those extended header fields, support for internationalization of delivery and service notifications [RFC3461] [RFC3464], and (finally) a requirement for support of the 8BITMIME SMTP extension [RFC6152] so that all of these can be transported through the mail system without having to overcome the limitation that header fields do not have content-transfer-encodings.