Additional Email Address Extension for the Extensible Provisioning Protocol (EPP)Karpatska 241/3Brno62500Czech Republic+420 603 261 036beldmit@gmail.comVeriSign, Inc.12061 Bluemont WayRestonVA20190United States of Americajgould@verisign.comhttps://www.verisign.comVerisign Labs12061 Bluemont WayRestonVA20190United States of Americashollenbeck@verisign.comhttps://www.verisignlabs.com/
ART
regextThe Extensible Provisioning Protocol (EPP) does not inherently support internationalized email addresses because the specifications for these addresses did not exist when EPP was developed. This document describes a command-response extension that adds support for associating an additional email address with an EPP contact object. That additional email address can be either an internationalized email address or an ASCII-only address.Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by
the Internet Engineering Steering Group (IESG). Further
information on Internet Standards is available in Section 2 of
RFC 7841.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
.
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Table of Contents
. Introduction
. Conventions Used in This Document
. Email Address Specification
. Additional Email Address Element
. Extension Considerations
. Signaling Client and Server Support
. Extension Behavior
. Extension Negotiated
. Extension Not Negotiated
. EPP Command Mapping
. EPP Query Commands
. EPP <check> Command
. EPP <info> Command
. EPP <transfer> Query Command
. EPP Transform Commands
. EPP <create> Command
. EPP <delete> Command
. EPP <renew> Command
. EPP <transfer> Command
. EPP <update> Command
. Formal Syntax
. EPP Additional Email Address Extension Schema
. IANA Considerations
. XML Namespace
. EPP Extension Registry
. Security Considerations
. Privacy Considerations
. References
. Normative References
. Informative References
Acknowledgments
Authors' Addresses
IntroductionThe framework for internationalized email addresses is described in . This document describes an Extensible Provisioning Protocol (EPP) command-response extension that adds support for adding a second email address to the EPP contact object mapping . The syntax for the email address associated with the base contact object is described in . The second email address can be either an ASCII-only email address or an internationalized SMTPUTF8 email address . This second address can be used to identify an alternate ASCII-only email address for use in case of primary address delivery issues. It can also be used to identify an SMTPUTF8 address for contact purposes, in which case the ASCII-only address can be used in case of SMTPUTF8 address delivery issues.While this extension adds support for an additional email address to contact objects, and that additional email address can be an SMTPUTF8 address, it does not in any way update or change any other EPP extension that includes an email address. Adding support for SMTPUTF8 addresses to those extensions will require an update to the relevant extension specifications. In cases where a contact object contains two email addresses, all users of these addresses should be aware that either address may be forwarded to the other. This implies that a message sent to an ASCII-only address may receive a reply from an SMTPUTF8 address or vice versa.Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14
when, and only when, they appear in all capitals, as shown here.
XML is case sensitive. Unless stated otherwise, XML specifications
and examples provided in this document MUST be interpreted in the
character case presented in order to develop a conforming
implementation.In examples, "C:" represents lines sent by a protocol client, and "S:" represents lines returned by a protocol server.
Indentation and white space in the examples are provided only to
illustrate element relationships and are not REQUIRED in the protocol.The XML namespace prefix "addlEmail" is used for the namespace
"urn:ietf:params:xml:ns:epp:addlEmail-1.0", but implementations MUST NOT depend on
it and instead MUST employ
a proper namespace-aware XML parser and serializer to interpret and
output the XML documents.Email Address SpecificationThe EPP contact object mapping normatively references as the specification for email address syntax. That specification does not include support for internationalized email addresses. provides an overview and describes the framework for internationalized email. SMTPUTF8 email address syntax is described in . extends the Mailbox, Local-part, and Domain ABNF rules in to support "UTF8-non-ascii" (defined in ) for the local-part and to support U-label (defined in ) for the domain. The validation rules described in MUST be followed when processing internationalized email addresses associated with this extension.Additional Email Address ElementA second email address can be set using the <addlEmail:addlEmail> element
with the command-response extensions defined in . The <addlEmail:addlEmail> element contains the following child element:
<addlEmail:email>:
An element following the syntax in for defining a second ASCII or SMTPUTF8 address. An empty <addlEmail:email/> element unsets
the second email address in the Update Command () and indicates the second email is not set in the Info Response ().
The <addlEmail:email> element contains an OPTIONAL "primary" attribute that can be used to indicate that the extension email address should be treated as the
primary email address for the extended contact object. The "primary" attribute MUST NOT be present if the <addlEmail:email> is empty.
Additional email address considerations:
The value set for the <contact:disclose><contact:email/> "flag" attribute (described in ) MUST also be applied to all additional email addresses that are added by a contact extension.
Any address included in an extension is intended to be an additional address that is associated only with the primary <contact:email> address, and support for any other additional email addresses MUST explicitly describe how the additional addresses are associated with the existing addresses.
Extension ConsiderationsSignaling Client and Server Support
As described in , the client and the server can signal support for the extension using a
namespace URI in the login and greeting extension services, respectively. The
namespace URI "urn:ietf:params:xml:ns:epp:addlEmail-1.0" is used to signal support for the extension.
The client includes the namespace URI in an <svcExtension> <extURI> element of
the <login> command . The server includes the namespace URI
in an <svcExtension> <extURI> element of the greeting .
Extension BehaviorExtension Negotiated
If both client and server have indicated support for SMTPUTF8 addresses during session establishment,
they MUST be able to process an SMTPUTF8 address in any extended contact object during the established EPP session. Server and client obligations when this extension has been successfully negotiated in the EPP session are described below.
The server MUST satisfy the following obligations when support for this extension has been negotiated:
Accept SMTPUTF8-compliant addresses for the extended contact object in the EPP session.
Support email address validation based on the SMTPUTF8 validation rules defined in .
Store email properties that support internationalized characters.
Return SMTPUTF8-compliant addresses for the extended contact object in EPP responses.
Support the SMTP extension for internationalized email described in when sending or receiving email.
The client MUST satisfy the following obligations when support for this extension has been negotiated:
Provide SMTPUTF8-compliant addresses for the extended contact object in the EPP session.
Accept SMTPUTF8-compliant addresses for the extended contact object in EPP responses.
Support the SMTP extension for internationalized email described in when sending or receiving email.
Extension Not NegotiatedAn extended contact object MUST NOT be provided or returned by either an EPP client or an EPP server when support for this extension is not successfully negotiated at the start of an EPP session.EPP Command MappingA detailed description of the EPP syntax and semantics can be found
in the EPP core protocol specification .
This section defines the provisioning of an alternate email address.EPP Query CommandsEPP provides three commands to retrieve object information: <check> to determine
if an object can be provisioned, <info> to retrieve information associated
with an object, and <transfer> to retrieve object-transfer status information.EPP <check> CommandThis extension does not add any elements to the EPP <check> command
or <check> response described in .EPP <info> CommandThis extension does not add any elements to the EPP <info> command
response described in .
If the query is successful, the server replies with an <addlEmail:addlEmail> element ()
along with the regular EPP <resData>.
Example <info> Contact Response Using the
<addlEmail:addlEmail> Extension with No Alternate Email Address
S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <contact:infData
S: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
S: <contact:id>sh8013</contact:id>
S: <contact:roid>SH8013-REP</contact:roid>
S: <contact:status s="linked"/>
S: <contact:status s="clientDeleteProhibited"/>
S: <contact:postalInfo type="int">
S: <contact:name>John Doe</contact:name>
S: <contact:org>Example Inc.</contact:org>
S: <contact:addr>
S: <contact:street>123 Example Dr.</contact:street>
S: <contact:street>Suite 100</contact:street>
S: <contact:city>Dulles</contact:city>
S: <contact:sp>VA</contact:sp>
S: <contact:pc>20166-6503</contact:pc>
S: <contact:cc>US</contact:cc>
S: </contact:addr>
S: </contact:postalInfo>
S: <contact:voice x="1234">+1.7035555555</contact:voice>
S: <contact:fax>+1.7035555556</contact:fax>
S: <contact:email>jdoe@example.com</contact:email>
S: <contact:clID>ClientY</contact:clID>
S: <contact:crID>ClientX</contact:crID>
S: <contact:crDate>1999-04-03T22:00:00.0Z</contact:crDate>
S: <contact:upID>ClientX</contact:upID>
S: <contact:upDate>1999-12-03T09:00:00.0Z</contact:upDate>
S: <contact:trDate>2000-04-08T09:00:00.0Z</contact:trDate>
S: <contact:authInfo>
S: <contact:pw>2fooBAR</contact:pw>
S: </contact:authInfo>
S: <contact:disclose flag="0">
S: <contact:voice/>
S: <contact:email/>
S: </contact:disclose>
S: </contact:infData>
S: </resData>
S: <extension>
S: <addlEmail:addlEmail
S: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
S: <addlEmail:email/>
S: </addlEmail:addlEmail>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S:</epp>Example <info> Contact Response Using the
<addlEmail:addlEmail> Extension with an Alternate ASCII Email Address
S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <contact:infData
S: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
S: <contact:id>sh8013</contact:id>
S: <contact:roid>SH8013-REP</contact:roid>
S: <contact:status s="linked"/>
S: <contact:status s="clientDeleteProhibited"/>
S: <contact:postalInfo type="int">
S: <contact:name>John Doe</contact:name>
S: <contact:org>Example Inc.</contact:org>
S: <contact:addr>
S: <contact:street>123 Example Dr.</contact:street>
S: <contact:street>Suite 100</contact:street>
S: <contact:city>Dulles</contact:city>
S: <contact:sp>VA</contact:sp>
S: <contact:pc>20166-6503</contact:pc>
S: <contact:cc>US</contact:cc>
S: </contact:addr>
S: </contact:postalInfo>
S: <contact:voice x="1234">+1.7035555555</contact:voice>
S: <contact:fax>+1.7035555556</contact:fax>
S: <contact:email>jdoe@example.com</contact:email>
S: <contact:clID>ClientY</contact:clID>
S: <contact:crID>ClientX</contact:crID>
S: <contact:crDate>1999-04-03T22:00:00.0Z</contact:crDate>
S: <contact:upID>ClientX</contact:upID>
S: <contact:upDate>1999-12-03T09:00:00.0Z</contact:upDate>
S: <contact:trDate>2000-04-08T09:00:00.0Z</contact:trDate>
S: <contact:authInfo>
S: <contact:pw>2fooBAR</contact:pw>
S: </contact:authInfo>
S: <contact:disclose flag="0">
S: <contact:voice/>
S: <contact:email/>
S: </contact:disclose>
S: </contact:infData>
S: </resData>
S: <extension>
S: <addlEmail:addlEmail
S: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
S: <addlEmail:email>jdoe-alt@example.net</addlEmail:email>
S: </addlEmail:addlEmail>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S:</epp>Example <info> Contact Response Using the
<addlEmail:addlEmail> Extension with an SMTPUTF8 Primary Email Address
S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <contact:infData
S: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
S: <contact:id>sh8013</contact:id>
S: <contact:roid>SH8013-REP</contact:roid>
S: <contact:status s="linked"/>
S: <contact:status s="clientDeleteProhibited"/>
S: <contact:postalInfo type="int">
S: <contact:name>John Doe</contact:name>
S: <contact:org>Example Inc.</contact:org>
S: <contact:addr>
S: <contact:street>123 Example Dr.</contact:street>
S: <contact:street>Suite 100</contact:street>
S: <contact:city>Dulles</contact:city>
S: <contact:sp>VA</contact:sp>
S: <contact:pc>20166-6503</contact:pc>
S: <contact:cc>US</contact:cc>
S: </contact:addr>
S: </contact:postalInfo>
S: <contact:voice x="1234">+1.7035555555</contact:voice>
S: <contact:fax>+1.7035555556</contact:fax>
S: <contact:email>jdoe@example.com</contact:email>
S: <contact:clID>ClientY</contact:clID>
S: <contact:crID>ClientX</contact:crID>
S: <contact:crDate>1999-04-03T22:00:00.0Z</contact:crDate>
S: <contact:upID>ClientX</contact:upID>
S: <contact:upDate>1999-12-03T09:00:00.0Z</contact:upDate>
S: <contact:trDate>2000-04-08T09:00:00.0Z</contact:trDate>
S: <contact:authInfo>
S: <contact:pw>2fooBAR</contact:pw>
S: </contact:authInfo>
S: <contact:disclose flag="0">
S: <contact:voice/>
S: <contact:email/>
S: </contact:disclose>
S: </contact:infData>
S: </resData>
S: <extension>
S: <addlEmail:addlEmail
S: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
S: <addlEmail:email
primary="true">麥克風@example.com</addlEmail:email>
S: </addlEmail:addlEmail>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S:</epp>EPP <transfer> Query CommandThis extension does not add any elements to the EPP <transfer> query command
or <transfer> query response described in .EPP Transform CommandsEPP provides five commands to transform objects: <create> to create an instance of an object,
<delete> to delete an instance of an object, <renew> to extend the validity period of an object,
<transfer> to manage object sponsorship changes, and <update> to change information associated
with an object.EPP <create> CommandThis extension defines additional elements to extend the EPP
<create> command described in .The EPP <create> command provides a transform operation that allows a client to create an instance of an object.
In addition to the EPP command elements described in , the command MUST contain a
child <addlEmail:addlEmail> element () for the client to set an alternate email address.Example <create> Command to Create a Contact Object with an Alternate ASCII Email Address
C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <create>
C: <contact:create
C: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
C: <contact:id>sh8013</contact:id>
C: <contact:postalInfo type="int">
C: <contact:name>John Doe</contact:name>
C: <contact:org>Example Inc.</contact:org>
C: <contact:addr>
C: <contact:street>123 Example Dr.</contact:street>
C: <contact:street>Suite 100</contact:street>
C: <contact:city>Dulles</contact:city>
C: <contact:sp>VA</contact:sp>
C: <contact:pc>20166-6503</contact:pc>
C: <contact:cc>US</contact:cc>
C: </contact:addr>
C: </contact:postalInfo>
C: <contact:voice x="1234">+1.7035555555</contact:voice>
C: <contact:fax>+1.7035555556</contact:fax>
C: <contact:email>jdoe@example.com</contact:email>
C: <contact:authInfo>
C: <contact:pw>2fooBAR</contact:pw>
C: </contact:authInfo>
C: <contact:disclose flag="0">
C: <contact:voice/>
C: <contact:email/>
C: </contact:disclose>
C: </contact:create>
C: </create>
C: <extension>
C: <addlEmail:addlEmail
C: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
C: <addlEmail:email>jdoe-alt@example.net</addlEmail:email>
C: </addlEmail:addlEmail>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C:</epp>Example <create> Command to Create a Contact Object with a Primary SMTPUTF8 Email Address
C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <create>
C: <contact:create
C: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
C: <contact:id>sh8013</contact:id>
C: <contact:postalInfo type="int">
C: <contact:name>John Doe</contact:name>
C: <contact:org>Example Inc.</contact:org>
C: <contact:addr>
C: <contact:street>123 Example Dr.</contact:street>
C: <contact:street>Suite 100</contact:street>
C: <contact:city>Dulles</contact:city>
C: <contact:sp>VA</contact:sp>
C: <contact:pc>20166-6503</contact:pc>
C: <contact:cc>US</contact:cc>
C: </contact:addr>
C: </contact:postalInfo>
C: <contact:voice x="1234">+1.7035555555</contact:voice>
C: <contact:fax>+1.7035555556</contact:fax>
C: <contact:email>jdoe@example.com</contact:email>
C: <contact:authInfo>
C: <contact:pw>2fooBAR</contact:pw>
C: </contact:authInfo>
C: <contact:disclose flag="0">
C: <contact:voice/>
C: <contact:email/>
C: </contact:disclose>
C: </contact:create>
C: </create>
C: <extension>
C: <addlEmail:addlEmail
C: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
C: <addlEmail:email
primary="true">麥克風@example.com</addlEmail:email>
C: </addlEmail:addlEmail>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C:</epp>This extension does not add any elements to the EPP <create> response described
in .EPP <delete> CommandThis extension does not add any elements to the EPP <delete> command
or <delete> response described in .EPP <renew> CommandThis extension does not add any elements to the EPP <renew> command
or <renew> response described in .EPP <transfer> CommandThis extension does not add any elements to the EPP <transfer> command
or <transfer> response described in .EPP <update> CommandThis extension defines additional elements to extend the EPP
<update> command described in .The EPP <update> command provides a transform operation that allows a client to update an instance of an object.
In addition to the EPP command elements described in , the command MUST contain a
child <addlEmail:addlEmail> element () for the client to set or unset an alternate email address.
If the alternate email address cannot be applied to the object, the server MUST return an EPP error result code of 2201.Example <update> Command to Set a Contact Object with an Alternate ASCII Email Address
C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <update>
C: <contact:update
C: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
C: <contact:id>sh8013</contact:id>
C: </contact:update>
C: </update>
C: <extension>
C: <addlEmail:addlEmail
C: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
C: <addlEmail:email>jdoe-alt@example.net</addlEmail:email>
C: </addlEmail:addlEmail>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C:</epp>Example <update> Command to Set a Contact Object with an Alternate SMTPUTF8 Email Address
C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <update>
C: <contact:update
C: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
C: <contact:id>sh8013</contact:id>
C: </contact:update>
C: </update>
C: <extension>
C: <addlEmail:addlEmail
C: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
C: <addlEmail:email>麥克風@example.com</addlEmail:email>
C: </addlEmail:addlEmail>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C:</epp>Example <update> Command to Unset a Contact Object Alternate Email Address
C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <update>
C: <contact:update
C: xmlns:contact="urn:ietf:params:xml:ns:contact-1.0">
C: <contact:id>sh8013</contact:id>
C: </contact:update>
C: </update>
C: <extension>
C: <addlEmail:addlEmail
C: xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0">
C: <addlEmail:email/>
C: </addlEmail:addlEmail>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C:</epp>This extension does not add any elements to the EPP <update> response described
in .Formal SyntaxThe EPP Additional Email Address Extension schema is presented here.The formal syntax shown here is a complete XML Schema representation of the object
mapping suitable for automated validation of EPP XML instances. The <CODE BEGINS>
and <CODE ENDS> tags are not part of the XML Schema; they are used to note the
beginning and ending of the XML Schema for URI registration purposes.EPP Additional Email Address Extension Schema
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:addlEmail="urn:ietf:params:xml:ns:epp:addlEmail-1.0"
targetNamespace="urn:ietf:params:xml:ns:epp:addlEmail-1.0"
elementFormDefault="qualified">
<annotation>
<documentation>Extensible Provisioning Protocol v1.0
additional email address schema.</documentation>
</annotation>
<!-- Create, Update, and Info Response extension element -->
<element name="addlEmail" type="addlEmail:addlEmailType" />
<!--
Single email element that can be empty
-->
<complexType name="addlEmailType">
<sequence>
<element name="email" type="addlEmail:emailType"/>
</sequence>
</complexType>
<complexType name="emailType">
<simpleContent>
<extension base="token">
<attribute name="primary" type="boolean" default="false"/>
</extension>
</simpleContent>
</complexType>
<!--
End of schema.
-->
</schema>IANA ConsiderationsXML Namespace This document uses URNs to describe XML namespaces and XML schemas
conforming to a registry mechanism described in . The following URI assignments have been made by IANA:
Registration for the addlEmail namespace:
URI:
urn:ietf:params:xml:ns:epp:addlEmail-1.0
Registrant Contact:
IESG
XML:
None. Namespace URIs do not represent an XML specification.
Registration for the addlEmail XML Schema:
URI:
urn:ietf:params:xml:schema:epp:addlEmail-1.0
Registrant Contact:
IESG
XML:
See of this document.
EPP Extension Registry
The EPP extension described in this document have been registered by
IANA in the "Extensions for the Extensible Provisioning Protocol
(EPP)" registry described in . The details of the
registration are as follows:
Name of Extension:
Additional Email Address Extension for the Extensible Provisioning Protocol (EPP)
Document Status:
Standards Track
Reference:
RFC 9873
Registrant Name and Email Address:
IESG, <iesg@ietf.org>
TLDs:
Any
IPR Disclosure:
None
Status:
Active
Notes:
None
Security ConsiderationsAs noted in Sections and of ,
unconstrained Unicode in email addresses can introduce a class of
security threats that do not exist with ASCII-only email addresses.
As EPP exists in ecosystems where email addresses passed in EPP are
displayed in the Registration Data Access Protocol (RDAP) and other services, and copy-and-paste of these
email addresses is common for businesses transferring domains via
EPP, there should be safeguards against these threats. Therefore,
use of the SMTPUTF8 email addresses as described in this document
SHOULD be done with policies that disallow the use of unconstrained
Unicode. The domain-part of these SMTPUTF8 email addresses SHOULD
conform to IDNA2008 . The local-part of these SMTPUTF8 email
addresses SHOULD be restricted to Unicode that does not introduce the
threats noted in . One such possible solution would be to
disallow characters outside of Unicode Annex 31 .
As an email address is often a primary end user contact, an invalid email address may put communication with the end user at risk when such contact is necessary. In case of an invalid domain name in the email address, a malicious actor can register a valid domain name with a similar U-label (homograph attack) and assume control over the domain name associated with the contact using social engineering techniques. To reduce the risk of the use of invalid domain names in email addresses, registries SHOULD validate the domain name syntax in provided email addresses and validate whether the domain name consists of the code points listed in the "IDNA Rules and Derived Property Values" registry ).Note that the syntax for internationalized email local-parts is very liberal.
Domains are normalized during MX lookup, while local-parts are unconstrained. Implementers may wish to test that their database is able to store difficult local-parts such as U+0061 U+0300 U+00E0. For more on normalization and these three code points, see .Privacy ConsiderationsThe content of <addlEmail:email> elements can be processed by EPP clients and servers in the same way that <contact:email> elements are processed, including publication in directory services such as RDAP . Many data protection regulations recognize email addresses as personal data, so any policies governing the collection, transmission, and processing of contact information by EPP clients and servers should apply equally to <addlEmail:email> elements.ReferencesNormative ReferencesKey words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.The IETF XML RegistryThis document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas.Simple Mail Transfer ProtocolThis document is a specification of the basic protocol for Internet electronic mail transport. It consolidates, updates, and clarifies several previous documents, making all or parts of most of them obsolete. It covers the SMTP extension mechanisms and best practices for the contemporary Internet, but does not provide details about particular extensions. Although SMTP was designed as a mail transport and delivery protocol, this specification also contains information that is important to its use as a "mail submission" protocol for "split-UA" (User Agent) mail reading systems and mobile environments. [STANDARDS-TRACK]Internet Message FormatThis document specifies the Internet Message Format (IMF), a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages. This specification is a revision of Request For Comments (RFC) 2822, which itself superseded Request For Comments (RFC) 822, "Standard for the Format of ARPA Internet Text Messages", updating it to reflect current practice and incorporating incremental changes that were specified in other RFCs. [STANDARDS-TRACK]Extensible Provisioning Protocol (EPP)This document describes an application-layer client-server protocol for the provisioning and management of objects stored in a shared central repository. Specified in XML, the protocol defines generic object management operations and an extensible framework that maps protocol operations to objects. This document includes a protocol specification, an object mapping template, and an XML media type registration. This document obsoletes RFC 4930. [STANDARDS-TRACK]Extensible Provisioning Protocol (EPP) Contact MappingThis document describes an Extensible Provisioning Protocol (EPP) mapping for the provisioning and management of individual or organizational social information identifiers (known as "contacts") stored in a shared central repository. Specified in Extensible Markup Language (XML), the mapping defines EPP command syntax and semantics as applied to contacts. This document obsoletes RFC 4933. [STANDARDS-TRACK]Internationalized Domain Names for Applications (IDNA): Definitions and Document FrameworkThis document is one of a collection that, together, describe the protocol and usage context for a revision of Internationalized Domain Names for Applications (IDNA), superseding the earlier version. It describes the document collection and provides definitions and other material that are common to the set. [STANDARDS-TRACK]Overview and Framework for Internationalized EmailFull use of electronic mail throughout the world requires that (subject to other constraints) people be able to use close variations on their own names (written correctly in their own languages and scripts) as mailbox names in email addresses. This document introduces a series of specifications that define mechanisms and protocol extensions needed to fully support internationalized email addresses. These changes include an SMTP extension and extension of email header syntax to accommodate UTF-8 data. The document set also includes discussion of key assumptions and issues in deploying fully internationalized email. This document is a replacement for RFC 4952; it reflects additional issues identified since that document was published. [STANDARDS-TRACK]SMTP Extension for Internationalized EmailThis document specifies an SMTP extension for transport and delivery of email messages with internationalized email addresses or header information. [STANDARDS-TRACK]Internationalized Email HeadersInternet mail was originally limited to 7-bit ASCII. MIME added support for the use of 8-bit character sets in body parts, and also defined an encoded-word construct so other character sets could be used in certain header field values. However, full internationalization of electronic mail requires additional enhancements to allow the use of Unicode, including characters outside the ASCII repertoire, in mail addresses as well as direct use of Unicode in header fields like "From:", "To:", and "Subject:", without requiring the use of complex encoded-word constructs. This document specifies an enhancement to the Internet Message Format and to MIME that allows use of Unicode in mail addresses and most header field content.This specification updates Section 6.4 of RFC 2045 to eliminate the restriction prohibiting the use of non-identity content-transfer- encodings on subtypes of "message/". [STANDARDS-TRACK]Ambiguity of Uppercase vs Lowercase in RFC 2119 Key WordsRFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.XML Schema Part 1: Structures Second EditionW3C RecommendationXML Schema Part 2: Datatypes Second EditionW3C RecommendationInformative ReferencesUnicode Format for Network InterchangeThe Internet today is in need of a standardized form for the transmission of internationalized "text" information, paralleling the specifications for the use of ASCII that date from the early days of the ARPANET. This document specifies that format, using UTF-8 with normalization and specific line-ending sequences. [STANDARDS-TRACK]Mapping Characters for Internationalized Domain Names in Applications (IDNA) 2008In the original version of the Internationalized Domain Names in Applications (IDNA) protocol, any Unicode code points taken from user input were mapped into a set of Unicode code points that "made sense", and then encoded and passed to the domain name system (DNS). The IDNA2008 protocol (described in RFCs 5890, 5891, 5892, and 5893) presumes that the input to the protocol comes from a set of "permitted" code points, which it then encodes and passes to the DNS, but does not specify what to do with the result of user input. This document describes the actions that can be taken by an implementation between receiving user input and passing permitted code points to the new IDNA protocol. This document is not an Internet Standards Track specification; it is published for informational purposes.Extension Registry for the Extensible Provisioning ProtocolThe Extensible Provisioning Protocol (EPP) includes features to add functionality by extending the protocol. It does not, however, describe how those extensions are managed. This document describes a procedure for the registration and management of extensions to EPP, and it specifies a format for an IANA registry to record those extensions.HTTP Usage in the Registration Data Access Protocol (RDAP)This document is one of a collection that together describes the Registration Data Access Protocol (RDAP). It describes how RDAP is transported using the Hypertext Transfer Protocol (HTTP). RDAP is a successor protocol to the very old WHOIS protocol. The purpose of this document is to clarify the use of standard HTTP mechanisms for this application.Security Services for the Registration Data Access Protocol (RDAP)The Registration Data Access Protocol (RDAP) provides "RESTful" web services to retrieve registration metadata from Domain Name and Regional Internet Registries. This document describes information security services, including access control, authentication, authorization, availability, data confidentiality, and data integrity for RDAP.Registration Data Access Protocol (RDAP) Query FormatThis document describes uniform patterns to construct HTTP URLs that may be used to retrieve registration information from registries (including both Regional Internet Registries (RIRs) and Domain Name Registries (DNRs)) using "RESTful" web access patterns. These uniform patterns define the query syntax for the Registration Data Access Protocol (RDAP). This document obsoletes RFC 7482.JSON Responses for the Registration Data Access Protocol (RDAP)This document describes JSON data structures representing registration information maintained by Regional Internet Registries (RIRs) and Domain Name Registries (DNRs). These data structures are used to form Registration Data Access Protocol (RDAP) query responses. This document obsoletes RFC 7483.Finding the Authoritative Registration Data Access Protocol (RDAP) ServiceThis document specifies a method to find which Registration Data Access Protocol (RDAP) server is authoritative to answer queries for a requested scope, such as domain names, IP addresses, or Autonomous System numbers. This document obsoletes RFC 7484.Unicode Identifiers and SyntaxVersion 16.0.0Latest version available at
.AcknowledgmentsThe authors would like to thank , , , , , , , ,
, , , , ,
, , , , , and
for their careful review and
valuable comments.Authors' AddressesKarpatska 241/3Brno62500Czech Republic+420 603 261 036beldmit@gmail.comVeriSign, Inc.12061 Bluemont WayRestonVA20190United States of Americajgould@verisign.comhttps://www.verisign.comVerisign Labs12061 Bluemont WayRestonVA20190United States of Americashollenbeck@verisign.comhttps://www.verisignlabs.com/