Regular Expressions for Internet Mail

Document Type Expired Internet-Draft (individual in art area)
Authors Sean Leonard  , Joe Hildebrand  , Tony Hansen 
Last updated 2019-05-09 (latest revision 2018-11-05)
Stream IETF
Intended RFC status Informational
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state (None)
Document shepherd No shepherd assigned
IESG IESG state Expired (IESG: Dead)
Consensus Boilerplate Unknown
Telechat date
Responsible AD Alexey Melnikov
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


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.


Sean Leonard (
Joe Hildebrand (
Tony Hansen (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)