Regular Expressions for Internet Mail
Sean Leonard, Tony Hansen, Joe Hildebrand · 2018
Internet Mail identifiers are used ubiquitously throughout computing systems as building blocks of online identity. Unfortunately, incomplete understandings of the syntaxes of these identifiers has led to interoperability problems and poor user experiences. Many users use specific characters in their addresses that are not properly accepted on various systems. This document prescribes normative regular expression (regex) patterns for all Internet- connected systems to use when validating or parsing Internet Mail identifiers, with special attention to regular expressions that work with popular languages and platforms.