TypeAlias.SupportedEmailLocale

type SupportedEmailLocale = "en-US" | "fr-FR" | "es-ES" | "it-IT";

BCP 47 language tags the backend i18n infrastructure ships email bundles for (nestjs-i18n + ICU MessageFormat, see ADR 0089). en-US is the source of truth; the others are translated bundles.

Distinct from ~/shared-types/enums/supported-locale.ts (SupportedLocale, EN/FR only), which scopes DPP content locales (product labels surfaced in the DPP App). The two domains are intentionally separate — email i18n ships four locales, DPP content currently two — so they must not be conflated.

Single source of truth for the supported email-locale list — import this instead of re-declaring z.enum([...]) (user/organization schemas, i18n resolvers, the i18n module fallback).