Interoperable Email Addresses for SMTPUTF8

This document specifies rules for email addresses that are flexible enough to express the addresses typically used with SMTPUTF8, while avoiding elements that harm human-to-human interoperation. This is one of a pair of documents: this contains recommendations for what addresses humans should use, such that address provisioning systems can restrain themselves to addresses that email valdidators accept. (This set can also be described in other ways, including "simple to cut-and-paste" and "understandable by some community".) Its companion defines simpler rules, accepts more addresses, and is intended for software like MTAs.