Internet Engineering Task Force (IETF)                          W. Mills
Request for Comments: 7293                                   Yahoo! Inc.
Category: Standards Track                                   M. Kucherawy
ISSN: 2070-1721                                           Facebook, Inc.
                                                               July 2014

The Require-Recipient-Valid-Since Header Field and SMTP Service Extension




This document defines an extension for the Simple Mail Transfer Protocol (SMTP) called "RRVS" to provide a method for senders to indicate to receivers a point in time when the ownership of the target mailbox was known to the sender. This can be used to detect changes of mailbox ownership and thus prevent mail from being delivered to the wrong party. This document also defines a header field called "Require-Recipient-Valid-Since" that can be used to tunnel the request through servers that do not support the extension.


The intended use of these facilities is on automatically generated messages, such as account statements or password change instructions, that might contain sensitive information, though it may also be useful in other applications.


Status of This Memo


This is an Internet Standards Track document.

これはInternet Standards Trackドキュメントです。

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 5741.

このドキュメントは、IETF(Internet Engineering Task Force)の製品です。これは、IETFコミュニティのコンセンサスを表しています。公開レビューを受け、インターネットエンジニアリングステアリンググループ(IESG)による公開が承認されました。インターネット標準の詳細については、RFC 5741のセクション2をご覧ください。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.

Copyright(c)2014 IETF Trustおよびドキュメントの作成者として識別された人物。全著作権所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

この文書は、BCP 78およびIETF文書に関するIETFトラストの法的規定(の対象であり、この文書の発行日に有効です。これらのドキュメントは、このドキュメントに関するあなたの権利と制限を説明しているため、注意深く確認してください。このドキュメントから抽出されたコードコンポーネントには、Trust Legal Provisionsのセクション4.eに記載されているSimplified BSD Licenseテキストが含まれている必要があり、Simplified BSD Licenseに記載されているように保証なしで提供されます。

Table of Contents


   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Description . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  The "RRVS" SMTP Extension . . . . . . . . . . . . . . . .   5
     3.2.  The "Require-Recipient-Valid-Since" Header Field  . . . .   5
     3.3.  Timestamps  . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Use By Generators . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Handling By Receivers . . . . . . . . . . . . . . . . . . . .   7
     5.1.  SMTP Extension Used . . . . . . . . . . . . . . . . . . .   7
       5.1.1.  Relays  . . . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  Header Field Used . . . . . . . . . . . . . . . . . . . .   9
       5.2.1.  Design Choices  . . . . . . . . . . . . . . . . . . .  10
     5.3.  Clock Synchronization . . . . . . . . . . . . . . . . . .  11
   6.  Relaying without RRVS Support . . . . . . . . . . . . . . . .  11
     6.1.  Header Field Conversion . . . . . . . . . . . . . . . . .  11
   7.  Header Field with Multiple Recipients . . . . . . . . . . . .  12
   8.  Special Use Addresses . . . . . . . . . . . . . . . . . . . .  13
     8.1.  Mailing Lists . . . . . . . . . . . . . . . . . . . . . .  13
     8.2.  Single-Recipient Aliases  . . . . . . . . . . . . . . . .  13
     8.3.  Multiple-Recipient Aliases  . . . . . . . . . . . . . . .  14
     8.4.  Confidential Forwarding Addresses . . . . . . . . . . . .  14
     8.5.  Suggested Mailing List Enhancements . . . . . . . . . . .  14
   9.  Continuous Ownership  . . . . . . . . . . . . . . . . . . . .  15
   10. Digital Signatures  . . . . . . . . . . . . . . . . . . . . .  15
   11. Authentication-Results Definitions  . . . . . . . . . . . . .  16
   12. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     12.1.  SMTP Extension Example . . . . . . . . . . . . . . . . .  17
     12.2.  Header Field Example . . . . . . . . . . . . . . . . . .  17
     12.3.  Authentication-Results Example . . . . . . . . . . . . .  17
   13. Security Considerations . . . . . . . . . . . . . . . . . . .  18
     13.1.  Abuse Countermeasures  . . . . . . . . . . . . . . . . .  18
     13.2.  Suggested Use Restrictions . . . . . . . . . . . . . . .  18
     13.3.  False Sense of Security  . . . . . . . . . . . . . . . .  18
     13.4.  Reassignment of Mailboxes  . . . . . . . . . . . . . . .  19
   14. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  19
     14.1.  The Tradeoff . . . . . . . . . . . . . . . . . . . . . .  19
     14.2.  Probing Attacks  . . . . . . . . . . . . . . . . . . . .  19
     14.3.  Envelope Recipients  . . . . . . . . . . . . . . . . . .  20
     14.4.  Risks with Use . . . . . . . . . . . . . . . . . . . . .  20
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
     15.1.  SMTP Extension Registration  . . . . . . . . . . . . . .  20
     15.2.  Header Field Registration  . . . . . . . . . . . . . . .  20
     15.3.  Enhanced Status Code Registration  . . . . . . . . . . .  21
     15.4.  Authentication Results Registration  . . . . . . . . . .  22
   16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  22
   17. References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     17.1.  Normative References . . . . . . . . . . . . . . . . . .  23
     17.2.  Informative References . . . . . . . . . . . . . . . . .  23
1. Introduction
1. はじめに

Email addresses sometimes get reassigned to a different person. For example, employment changes at a company can cause an address used for an ex-employee to be assigned to a new employee, or a mail service provider (MSP) might expire an account and then let someone else register for the local-part that was previously used. Those who sent mail to the previous owner of an address might not know that it has been reassigned. This can lead to the sending of email to the correct address but the wrong recipient. This situation is of particular concern with transactional mail related to purchases, online accounts, and the like.


What is needed is a way to indicate an attribute of the recipient that will distinguish between the previous owner of an address and its current owner, if they are different. Further, this needs to be done in a way that respects privacy.


The mechanisms specified here allow the sender of the mail to indicate how "old" the address assignment is expected to be. In effect, the sender is saying, "I know that the intended recipient was using this address at this point in time. I don't want this message delivered to anyone else". A receiving system can then compare this information against the point in time at which the address was assigned to its current user. If the assignment was made later than the point in time indicated in the message, there is a good chance the current user of the address is not the correct recipient. The receiving system can then prevent delivery and, preferably, notify the original sender of the problem.


The primary application is transactional mail (such as account information, password change requests, and other automatically generated messages) rather than user-authored content. However, it may be useful in other contexts; for example, a personal address book could record the time an email address was added to it, and thus use that time with this extension.


Because the use cases for this extension are strongly tied to privacy issues, attention to the Security Considerations (Section 13) and the Privacy Considerations (Section 14) is particularly important. Note, especially, the limitation described in Section 13.3.


2. Definitions
2. 定義

For a description of the email architecture, consult [EMAIL-ARCH].


The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [KEYWORDS].

このドキュメントのキーワード「MUST」、「MUST NOT」、「REQUIRED」、「SHALL」、「SHALL NOT」、「SHOULD」、「SHOULD NOT」、「RECOMMENDED」、「MAY」、および「OPTIONAL」は、 [キーワード]で説明されているように解釈されます。

3. Description
3. 説明

To address the problem described in Section 1, a mail-sending client (usually an automated agent) needs to indicate to the server to which it is connecting that it expects the destination address of the message to have been under continuous ownership (see Section 9) since a specified point time. That specified time would be the time when the intended recipient gave the address to the message author, or perhaps a more recent time when the intended recipient reconfirmed ownership of the address with the sender.

セクション1で説明されている問題に対処するには、メール送信クライアント(通常は自動エージェント)が、接続先のサーバーに、メッセージの宛先アドレスが継続的な所有権であると期待していることを示す必要があります(セクション9を参照)。 )指定された時点以降。その特定の時間は、意図された受信者がメッセージの作成者にアドレスを提供した時間、またはおそらくより最近の時間は、意図された受信者が送信者にアドレスの所有権を再確認したときです。

Two mechanisms are defined here: an extension to the Simple Mail Transfer Protocol [SMTP] and a new message header field. The SMTP extension permits strong assurance of enforcement by confirming support at each handling step for a message and the option to demand support at all nodes in the handling path of the message (and returning of the message to the originator otherwise). The header field can be used when the Message Delivery Agent (MDA) supports this function, but an intermediary system between the sending system and the MDA does not. However, the header field does not provide the same strong assurance described above and is more prone to exposure of private information (see Section 14.1).

ここでは2つのメカニズムが定義されています。SimpleMail Transfer Protocol [SMTP]の拡張と新しいメッセージヘッダーフィールドです。 SMTP拡張機能を使用すると、メッセージの各処理ステップでサポートを確認し、メッセージの処理パス内のすべてのノードでサポートを要求するオプションを確認することで、施行を強力に保証できます(それ以外の場合はメッセージを発信者に返す)。ヘッダーフィールドは、メッセージ配信エージェント(MDA)がこの機能をサポートしている場合に使用できますが、送信システムとMDAの間の中間システムはサポートしていません。ただし、ヘッダーフィールドは上記と同じ強力な保証を提供せず、個人情報が公開される傾向があります(セクション14.1を参照)。

The SMTP extension is called "RRVS" and adds a parameter to the SMTP "RCPT" command that indicates the most recent point in time when the message author believed the destination mailbox to be under the continuous ownership of a specific party. Similarly, the "Require-Recipient-Valid-Since" header field includes an intended recipient coupled with a timestamp indicating the same thing.


3.1. The "RRVS" SMTP Extension
3.1. 「RRVS」SMTP拡張機能

Extensions to SMTP are described in Section 2.2 of [SMTP].


The name of the extension is "RRVS", an abbreviation of "Require Recipient Valid Since". Servers implementing the SMTP extension advertise an additional EHLO keyword of "RRVS", which has no associated parameters, introduces no new SMTP commands, and does not alter the MAIL command.

拡張子の名前は「RRVS」であり、「Require Recipient Valid since」の省略形です。 SMTP拡張機能を実装するサーバーは、関連するパラメーターがなく、新しいSMTPコマンドを導入せず、MAILコマンドを変更しない「RRVS」という追加のEHLOキーワードをアドバタイズします。

A Message Transfer Agent (MTA) implementing RRVS can transmit or accept one new parameter to the RCPT command. An MDA can also accept this new parameter. The parameter is "RRVS", and the value is a timestamp expressed as "date-time" as defined in [DATETIME], with the added restriction that a "time-secfrac" MUST NOT be used. The timestamp MAY optionally be followed by a semicolon character and a letter (known as the "no-support action"), indicating the action to be taken when a downstream MTA is discovered that does not support the extension. Valid actions are "R" (reject; the default) and "C" (continue).

RRVSを実装するメッセージ転送エージェント(MTA)は、RCPTコマンドに1つの新しいパラメーターを送信または受け入れることができます。 MDAもこの新しいパラメーターを受け入れることができます。パラメータは「RRVS」で、値は[datetime]で定義された「date-time」で表されるタイムスタンプです。「time-secfrac」を使用してはならないという制限が追加されています。タイムスタンプの後ろには、オプションでセミコロン文字と文字(「no-supportアクション」と呼ばれる)を付けることができます。これは、拡張をサポートしないダウンストリームMTAが検出されたときに実行するアクションを示します。有効なアクションは、「R」(拒否、デフォルト)および「C」(続行)です。

Formally, the new parameter and its value are defined as follows:


       rrvs-param = "RRVS=" date-time [ ";" ( "C" / "R" ) ]

Accordingly, this extension increases the maximum command length for the RCPT command by 33 characters.


The meaning of this extension, when used, is described in Section 5.1.


3.2. The "Require-Recipient-Valid-Since" Header Field
3.2. 「Require-Recipient-Valid-Since」ヘッダーフィールド

The general constraints on syntax and placement of header fields in a message are defined in "Internet Message Format" [MAIL].


Using Augmented Backus-Naur Form [ABNF], the syntax for the field is:


rrvs = "Require-Recipient-Valid-Since:" addr-spec ";" date-time CRLF

rrvs = "Require-Recipient-Valid-Since:" addr-spec ";"日時CRLF

"date-time" is defined in Section 3.3, and "addr-spec" is defined in Section 3.4.1 of [MAIL].


3.3. Timestamps
3.3. タイムスタンプ

The header field version of this protocol has a different format for the date and time expression than the SMTP extension does. This is because message header fields use a format to express date and time that is specific to message header fields, and this is consistent with that usage.


Use of both date and time is done to be consistent with how current implementations typically store the timestamp and to make it easy to include the time zone. In practice, granularity beyond the date may or may not be useful.


4. Use By Generators
4. ジェネレータによる使用

When a message is generated whose content is sufficiently sensitive that an author or author's ADministrative Management Domain (ADMD), see [EMAIL-ARCH], wishes to protect against misdelivery using this protocol, it determines for each recipient mailbox on the message a timestamp at which it last confirmed ownership of that mailbox. It then applies the SMTP extension when sending the message to its destination.


In cases where the outgoing MTA does not support the extension, the header field defined above can be used to pass the request through that system. However, use of the header field is only a "best-effort" approach to solving the stated goals, and it has some shortcomings:


1. The positive confirmation of support at each handling node, with the option to return the message to the originator when end-to-end support cannot be confirmed, will be unavailable;

1. 各処理ノードでのサポートの確実な確認は、エンドツーエンドのサポートが確認できない場合にメッセージを発信者に返すオプションで、利用できなくなります。

2. The protocol is focused on affecting delivery (that is, the transaction) rather than content, and therefore use of a header field in the content is generally inappropriate;

2. このプロトコルはコンテンツではなく配信(つまりトランザクション)に影響を与えることに焦点を当てているため、コンテンツでのヘッダーフィールドの使用は一般に不適切です。

3. The mechanism cannot be used with multiple recipients without unintentionally exposing information about one recipient to the others (see Section 7); and

3. このメカニズムは、1人の受信者に関する情報を意図せずに他の人に公開しない限り、複数の受信者で使用できません(セクション7を参照)。そして

4. There is a risk of the timestamp parameter being inadvertently forwarded, automatically or intentionally by the user (since user agents might not reveal the presence of the header field), and therefore exposed to unintended recipients. (See Section 14.4.)

4. (ユーザーエージェントがヘッダーフィールドの存在を明らかにしない可能性があるため)タイムスタンプパラメーターがユーザーによって誤って自動または意図的に転送され、意図しない受信者に公開されるリスクがあります。 (14.4項を参照してください。)

Thus, the header field format MUST NOT be used unless the originator or relay has specific knowledge that the receiving MDA or an intermediary MTA will apply it properly. In any case, it SHOULD NOT be used for the multi-recipient case.

したがって、ヘッダーフィールドフォーマットは、発信者またはリレーが受信MDAまたは中間MTAが適切に適用するという特定の知識がない限り、使用してはなりません(MUST NOT)。いずれの場合も、複数受信者の場合には使用しないでください。

Use of the header field mechanism is further restricted by the practices described in Section 7.2 of [SMTP], Section 3.6.3 of [MAIL], and Section 7 of this document.


5. Handling By Receivers
5. 受信者による処理

If a receiver implements this specification, then there are two possible evaluation paths:


1. The sending client uses the extension, and so there is an RRVS parameter on a RCPT TO command in the SMTP session, and the parameters of interest are taken only from there (and the header field, if present, is disregarded); or

1. 送信側クライアントは拡張機能を使用するため、SMTPセッションのRCPT TOコマンドにRRVSパラメータがあり、関係するパラメータはそこからのみ取得されます(存在する場合、ヘッダーフィールドは無視されます)。または

2. The sending client does not use the extension, so the RRVS parameter is not present on the RCPT TO commands in the SMTP session, but the corresponding header field might be present in the message.

2. 送信側クライアントは拡張機能を使用しないため、SMTPセッションのRCPT TOコマンドにRRVSパラメータはありませんが、対応するヘッダーフィールドがメッセージに存在する場合があります。

When the continuous ownership test fails for transient reasons (such as an unavailable database or other condition that is likely temporary), normal transient failure handling for the message is applied.


If the continuous ownership test cannot be completed because the necessary datum (the mailbox creation or reassignment date and time) was not recorded, the MDA doing the evaluation selects a date and time to use that is the latest possible point in time at which the mailbox could have been created or reassigned. For example, this might be the earliest of all recorded mailbox creation/reassignment timestamps, or the time when the host was first installed. If no reasonable substitute for the timestamp can be selected, the MDA rejects the message using an SMTP reply code, preferably with an enhanced mail system status code (see Section 15.3), that indicates the test cannot be completed. A message originator can then decide whether to reissue the message without RRVS protection or find another way to reach the mailbox owner.


5.1. SMTP Extension Used
5.1. 使用するSMTP拡張機能

For an MTA supporting the SMTP extension, the requirement is to continue enforcement of RRVS during the relaying process to the next MTA or the MDA.


A receiving MTA or MDA that implements the SMTP extension declared above and observes an RRVS parameter on a RCPT TO command checks whether the current owner of the destination mailbox has held it continuously, far enough back to include the given point in time, and delivers it unless that check returns in the negative. Specifically, an MDA will do the following before continuing with delivery:

上記で宣言されたSMTP拡張機能を実装し、RCPT TOコマンドのRRVSパラメータを監視する受信MTAまたはMDAは、宛先メールボックスの現在の所有者が継続的に、指定された時点を含むのに十分なだけそれを保持しているかどうかをチェックし、配信しますそのチェックが否定的に返らない限り。具体的には、MDAは配信を続行する前に次のことを行います。

1. Ignore the parameter if the named mailbox is known to be a role account as listed in "Mailbox Names for Common Services, Roles and Functions" [ROLES].

1. 「共通サービス、役割、機能のメールボックス名」[ROLES]にリストされているように、名前付きメールボックスが役割アカウントであることがわかっている場合は、パラメーターを無視してください。

2. If the address is not known to be a role account, and if that address has not been under continuous ownership since the timestamp specified in the extension, return a 550 error to the RCPT command. (See also Section 15.3.)

2. アドレスが役割アカウントであることがわからない場合、および拡張で指定されたタイムスタンプ以降、そのアドレスが継続的な所有権を持っていない場合は、RCPTコマンドに550エラーを返します。 (セクション15.3も参照してください。)

5.1.1. Relays
5.1.1. リレー

An MTA that does not make mailbox ownership checks, such as an MTA positioned to do SMTP ingress at an organizational boundary, SHOULD relay the RRVS extension parameter to the next MTA or MDA so that it can be processed there.


For the SMTP extension, the optional RRVS parameter defined in Section 5.1 indicates the action to be taken when relaying a message to another MTA that does not advertise support for this extension. When this is the case and the no-support action was not specified or is "R" (reject), the MTA handling the message MUST reject the message by:


1. returning a 550 error to the DATA command, if synchronous service is being provided to the SMTP client that introduced the message, or

1. メッセージを導入したSMTPクライアントに同期サービスが提供されている場合、DATAコマンドに550エラーを返す、または

2. generating a Delivery Status Notification [DSN] to indicate to the originator of the message that the non-delivery occurred and terminating further relay attempts.

2. 配信ステータス通知[DSN]を生成して、配信不能が発生したことをメッセージの発信者に通知し、それ以降のリレー試行を終了します。

An enhanced mail system status code is defined for such rejections in Section 15.3.


See Section 8.2 for additional discussion.


When relaying, an MTA MUST preserve the no-support action if it was used by the SMTP client.


5.2. Header Field Used
5.2. 使用するヘッダーフィールド

A receiving system that implements this specification, upon receiving a message bearing a "Require-Recipient-Valid-Since" header field when no corresponding RRVS SMTP extension was used, checks whether the destination mailbox owner has held it continuously, far enough back to include the given date-time, and delivers it unless that check returns in the negative. Expressed as a sequence of steps:

この仕様を実装する受信システムは、対応するRRVS SMTP拡張機能が使用されなかった場合に「Require-Recipient-Valid-Since」ヘッダーフィールドが付いたメッセージを受信すると、宛先メールボックスの所有者が継続的にそれを保持できるかどうかをチェックします。指定された日時。そのチェックが否定的に返らない限り、それを配信します。ステップのシーケンスとして表されます:

1. Extract those Require-Recipient-Valid-Since fields from the message that contain a recipient for which no corresponding RRVS SMTP extension was used.

1. 対応するRRVS SMTP拡張が使用されなかった受信者を含むメッセージから、それらのRequire-Recipient-Valid-Sinceフィールドを抽出します。

2. Discard any such fields that match any of these criteria:

2. 次の基準のいずれかに一致するフィールドは破棄してください。

* are syntactically invalid;

* 構文的に無効です。

* name a role account as listed in [ROLES];

* [ROLES]にリストされているように役割アカウントに名前を付けます。

* the "addr-spec" portion does not match a current recipient, as listed in the RCPT TO commands in the SMTP session; or

* SMTPセッションのRCPT TOコマンドにリストされているように、「addr-spec」部分は現在の受信者と一致しません。または

* the "addr-spec" portion does not refer to a mailbox handled for local delivery by this ADMD.

* 「addr-spec」の部分は、このADMDによるローカル配信用に処理されるメールボックスを指していません。

3. For each field remaining, determine if the named address has been under continuous ownership since the corresponding timestamp. If it has not, reject the message.

3. 残りの各フィールドについて、指定されたアドレスが、対応するタイムスタンプ以降、継続的に所有されているかどうかを確認します。そうでない場合は、メッセージを拒否します。

4. RECOMMENDED: If local delivery is being performed, remove all instances of this field prior to delivery to a mailbox; if the message is being forwarded, remove those instances of this header field that were not discarded by step 2 above.

4. 推奨:ローカル配信を実行している場合は、メールボックスに配信する前に、このフィールドのすべてのインスタンスを削除してください。メッセージが転送されている場合は、上記の手順2で破棄されなかったこのヘッダーフィールドのインスタンスを削除します。

Handling proceeds normally upon completion of the above steps if rejection has not been performed.


The final step is not mandatory as not all mail handling agents are capable of stripping away header fields, and there are sometimes reasons to keep the field intact such as debugging or presence of digital signatures that might be invalidated by such a change. See Section 10 for additional discussion.


If a message is to be rejected within the SMTP protocol itself (versus generating a rejection message separately), servers implementing this protocol SHOULD also implement the SMTP extension described in "Enhanced Mail System Status Codes" [ESC] and use the enhanced status codes described in Section 15.3 as appropriate.


Implementation by this method is expected to be transparent to non-participants, since they would typically ignore this header field.


This header field is not normally added to a message that is addressed to multiple recipients. The intended use of this field involves an author seeking to protect transactional or otherwise sensitive data intended for a single recipient, and thus generating independent messages for each individual recipient is normal practice. See Section 7 for further discussion and restrictions.


5.2.1. Design Choices
5.2.1. デザインの選択

The presence of the address in the field content supports the case where a message bearing this header field is forwarded. The specific use case is as follows:


1. A user subscribes to a service "S" at date-time "D" and confirms an email address at the user's current location, "A";

1. ユーザーは日時「D」にサービス「S」に登録し、ユーザーの現在の場所「A」にあるメールアドレスを確認します。

2. At some later date, the user intends to leave the current location and thus creates a new mailbox elsewhere, at "B";

2. 後日、ユーザーは現在の場所を離れようとするため、「B」に別の場所に新しいメールボックスを作成します。

3. The user configures address "A" to forward to "B";

3. ユーザーはアドレス「A」を「B」に転送するように構成します。

4. "S" constructs a message to "A" claiming that the address was valid at date-time "D" and sends it to "A";

4. "S"は、アドレスが日時 "D"で有効であったと主張する "A"へのメッセージを作成し、 "A"に送信します。

5. The receiving MTA for "A" determines that the forwarding in effect was created by the same party that owned the mailbox there and thus concludes that the continuous ownership test has been satisfied;

5. 「A」の受信MTAは、実際に転送がそこでメールボックスを所有していた同じ当事者によって作成されたと判断し、継続的な所有権テストが満たされていると結論付けます。

6. If possible, the MTA for "A" removes this header field from the message, and in either case, forwards it to "B"; and

6. 可能であれば、「A」のMTAはこのヘッダーフィールドをメッセージから削除し、どちらの場合も「B」に転送します。そして

7. On receipt at "B", either the header field has been removed or the header field does not refer to a current envelope recipient, and in either case the MTA delivers the message.

7. 「B」で受信すると、ヘッダーフィールドが削除されているか、ヘッダーフィールドが現在のエンベロープ受信者を参照していないか、どちらの場合でもMTAがメッセージを配信します。

Section 8 discusses some interesting use cases, such as the case where "B" above results in further forwarding of the message.


SMTP has never required any correspondence between addresses in the RFC5321.MailFrom and RFC5321.RcptTo parameters and header fields of a message, which is why the header field defined here contains the recipient address to which the timestamp applies.


5.3. Clock Synchronization
5.3. クロック同期

The timestamp portion of this specification supports a precision at the seconds level. Although uncommon, it is not impossible for a clock at either a generator or a receiver to be incorrect, leading to an incorrect result in the RRVS evaluation.


To minimize the risk of such incorrect results, both generators and receivers implementing this specification MUST use a standard clock synchronization protocol such as [NTP] to synchronize to a common clock.


6. Relaying without RRVS Support
6. RRVSサポートなしのリレー

When a message is received using the SMTP extension defined here but will not be delivered locally (that is, it needs to be relayed further), the MTA to which the relay will take place might not be compliant with this specification. Where the MTA in possession of the message observes it is going to relay the message to an MTA that does not advertise this extension, it needs to choose one of the following actions:


1. Decline to relay the message further, preferably generating a Delivery Status Notification [DSN] to indicate failure (RECOMMENDED);

1. さらにメッセージを中継することを拒否し、できれば配信ステータス通知[DSN]を生成して失敗を示します(推奨)。

2. Downgrade the data thus provided in the SMTP extension to a header field, as described in Section 6.1 below (SHOULD NOT unless the conditions in that section are satisfied, and only when the previous option is not available); or

2. 以下のセクション6.1で説明されているように、SMTP拡張でこのように提供されたデータをヘッダーフィールドにダウングレードします(そのセクションの条件が満たされていない限り、かつ前のオプションが利用できない場合のみ)。または

3. Silently continue with delivery, dropping the protection offered by this protocol.

3. 静かに配信を続行し、このプロトコルによって提供される保護を削除します。

Using options other than the first option needs to be avoided unless there is specific knowledge that further relaying with the degraded protections thus provided does not introduce undue risk.


6.1. Header Field Conversion
6.1. ヘッダーフィールドの変換

If an SMTP server ("B") receives a message bearing one or more "Require-Recipient-Valid-Since" header fields from a client ("A"), presumably because "A" does not support the SMTP extension, and needs to relay the corresponding message on to another server ("C") (thereby becoming a client), and "C" advertises support for the SMTP extension, "B" SHOULD delete the header field(s) and instead relay this information by making use of the SMTP extension. Note that such modification of the header might affect later validation of the header upon delivery; for example, a hash of the modified header would produce a different result. This might be a valid cause for some operators to skip this delete operation.

SMTPサーバー( "B")が1つ以上の "Require-Recipient-Valid-Since"ヘッダーフィールドを持つメッセージをクライアント( "A")から受信した場合、おそらく "A"はSMTP拡張機能をサポートしていないため、対応するメッセージを別のサーバー( "C")に中継し(それによってクライアントになる)、 "C"がSMTP拡張のサポートをアドバタイズするには、 "B"はヘッダーフィールドを削除し、代わりにSMTP拡張機能の使用。このようなヘッダーの変更は、配信後のヘッダーの検証に影響を与える可能性があることに注意してください。たとえば、変更されたヘッダーのハッシュは異なる結果を生成します。これは、一部のオペレーターがこの削除操作をスキップする正当な原因である可能性があります。

Conversely, if "B" has received a mailbox timestamp from "A" using the SMTP extension for which it must now relay the message on to "C", but "C" does not advertise the SMTP extension, and "B" does not reject the message because rejection was specifically declined by the client (see Section 5.1.1), "B" SHOULD add a Require-Recipient-Valid-Since header field matching the mailbox to which relaying is being done, and the corresponding valid-since timestamp for it, if it has prior information that the eventual MDA or another intermediate MTA supports this mechanism and will be able to process the header field as described in this specification.


The admonitions about very cautious use of the header field described in Section 4 apply to this relaying mechanism as well. If multiple mailbox timestamps are received from "A", the admonitions in Section 7 also apply.

セクション4で説明されているヘッダーフィールドの非常に注意深い使用に関する警告は、このリレーメカニズムにも適用されます。 「A」から複数のメールボックスタイムスタンプを受信した場合、セクション7の警告も適用されます。

7. Header Field with Multiple Recipients
7. 複数の受信者を持つヘッダーフィールド

Numerous issues arise when using the header field form of this extension, particularly when multiple recipients are specified for a single message resulting in multiple fields each with a distinct address and timestamp.


Because of the nature of SMTP, a message bearing a multiplicity of Require-Recipient-Valid-Since header fields could result in a single delivery attempt for multiple recipients (in particular, if two of the recipients are handled by the same server), and if any one of them fails the test, the delivery fails to all of them; it then becomes necessary to do one of the following:


o reject the message on completion of the DATA phase of the SMTP session, which is a rejection of delivery to all recipients, or

o SMTPセッションのDATAフェーズの完了時にメッセージを拒否します。これは、すべての受信者への配信の拒否です。

o accept the message on completion of DATA, and then generate a Delivery Status Notification [DSN] message for each of the failed recipients.

o DATAの完了時にメッセージを受け入れ、失敗した受信者ごとに配信ステータス通知[DSN]メッセージを生成します。

Additional complexity arises when a message is sent to two recipients, "A" and "B", presumably with different timestamps, both of which are then redirected to a common address "C". The author is not necessarily aware of the current or past ownership of mailbox "C", or indeed that "A" and/or "B" have been redirected. This might result in either or both of the two deliveries failing at "C", which is likely to confuse the message author, who (as far as the author is aware) never sent a message to "C" in the first place.


Finally, there is an obvious concern with the fan-out of a message bearing the timestamps of multiple users; tight control over the handling of the timestamp information is very difficult to assure as the number of handling agents increases.


8. Special Use Addresses
8. 特別使用アドレス

In [DSN-SMTP], an SMTP extension was defined to allow SMTP clients to request generation of DSNs and related information to allow such reports to be maximally useful. Section 5.2.7 of that document explored the issue of the use of that extension where the recipient is a mailing list. This extension has similar concerns, which are covered here following that document as a model.


For all cases described below, a receiving MTA SHOULD NOT introduce RRVS in either form (SMTP extension or header field) if the message did not arrive with RRVS in use. This would amount to second guessing the message originator's intention and might lead to an undesirable outcome.

以下に説明するすべてのケースで、メッセージがRRVSの使用中に到着しなかった場合、受信MTAはどちらの形式(SMTP拡張またはヘッダーフィールド)でもRRVSを導入してはなりません(SHOULD NOT)。これは、メッセージの発信者の意図を2番目に推測することになり、望ましくない結果につながる可能性があります。

8.1. Mailing Lists
8.1. メーリングリスト

Delivery to a mailing list service is considered a final delivery. Where this protocol is in use, it is evaluated as per any normal delivery: if the same mailing list has been operating in place of the specified recipient mailbox since at least the timestamp given as the RRVS parameter, the message is delivered to the list service normally, and is otherwise not delivered.


It is important, however, that the participating MDA passing the message to the list service needs to omit the RRVS parameter in either form (SMTP extension or header field) when doing so. The emission of a message from the list service to its subscribers constitutes a new message not covered by the previous transaction.


8.2. Single-Recipient Aliases
8.2. 単一受信者エイリアス

Upon delivery of an RRVS-protected message to an alias (acting in place of a mailbox) that results in relaying of the message to a single other destination, the usual RRVS check is performed. The continuous ownership test here might succeed if, for example, a conventional user inbox was replaced with an alias on behalf of that same user, and the time when this was done is recorded in a way that can be queried by the relaying MTA.


If the relaying system also performs some kind of step where ownership of the new destination address is confirmed, it SHOULD apply RRVS using the later of that timestamp and the one that was used inbound. This also allows for changes to the alias without disrupting the protection offered by RRVS.


If the relaying system has no such time records related to the new destination address, the RRVS SMTP extension is not used on the relaying SMTP session, and the header field relative to the local alias is removed, in accordance with Section 5.

中継システムに新しい宛先アドレスに関連するそのようなタイムレコードがない場合、RRVS SMTP拡張は中継SMTPセッションで使用されず、ローカルエイリアスに関連するヘッダーフィールドがセクション5に従って削除されます。

8.3. Multiple-Recipient Aliases
8.3. 複数の受信者のエイリアス

Upon delivery of an RRVS-protected message to an alias (acting in place of a mailbox) that results in relaying of the message to multiple other destinations, the usual RRVS check is performed as in Section 8.2. The MTA expanding such an alias then decides which of the options enumerated in that section is to be applied for each new recipient.


8.4. Confidential Forwarding Addresses
8.4. 機密転送アドレス

In the above cases, the original author could receive message rejections, such as DSNs, from the ultimate destination, where the RRVS check (or indeed, any other) fails and rejection is warranted. This can reveal the existence of a forwarding relationship between the original intended recipient and the actual final recipient.


Where this is a concern, the initial delivery attempt is to be treated like a mailing list delivery, with RRVS evaluation done and then all RRVS information removed from the message prior to relaying it to its true destination.


8.5. Suggested Mailing List Enhancements
8.5. 推奨されるメーリングリストの機能強化

Mailing list services could store the timestamp at which a subscriber was added to a mailing list. This specification could then be used in conjunction with that information in order to restrict list traffic to the original subscriber, rather than a different person now in possession of an address under which the original subscriber was added to the list. Upon receiving a rejection caused by this specification, the list service can remove that address from further distribution.


A mailing list service that receives a message containing the header field defined here needs to remove it from the message prior to redistributing it, limiting exposure of information regarding the relationship between the message's author and the mailing list.


9. Continuous Ownership
9. 継続的な所有権

For the purposes of this specification, an address is defined as having been under continuous ownership since a given date-time if a message sent to the address at any point since the given date-time would not go to anyone except the owner at that given date-time. That is, while an address may have been suspended or otherwise disabled for some period, any mail actually delivered would have been delivered exclusively to the same owner. It is presumed that some sort of relationship exists between the message sender and the intended recipient. Presumably, there has been some confirmation process applied to establish this ownership of the receiver's mailbox; however, the method of making such determinations is a local matter and outside the scope of this document.


Evaluating the notion of continuous ownership is accomplished by doing any query that establishes whether the above condition holds for a given mailbox.


Determining continuous ownership of a mailbox is a local matter at the receiving site. The only possible answers to the continuous-ownership-since question are "yes", "no", and "unknown"; the action to be taken in the "unknown" case is a matter of local policy.

メールボックスの継続的な所有権を決定することは、受信サイトのローカルな問題です。継続的所有権以降の質問に対する唯一の可能な回答は、「はい」、「いいえ」、および「不明」です。 「不明」のケースで取られるアクションは、ローカルポリシーの問題です。

For example, when control of a domain name is transferred, the new domain owner might be unable to determine whether the owner of the subject address has been under continuous ownership since the stated date-time if the mailbox history is not also transferred (or was not previously maintained). It will also be "unknown" if whatever database contains mailbox ownership data is temporarily unavailable at the time a message arrives for delivery. In this latter case, typical SMTP temporary failure handling is appropriate.


To avoid exposing account details unnecessarily, if the address specified has had one continuous owner since it was created, any confirmation date-time SHOULD be considered to pass the test, even if that date-time is earlier than the account creation date and time. This is further discussed in Section 13.


10. Digital Signatures
10. デジタル署名

This protocol mandates removal of the header field (when used) upon delivery in all but exceptional circumstances. If a message with the header field were digitally signed in a way that included the header field, altering a message in this way would invalidate the signature. However, the header field is strictly for tunneling purposes and should be regarded by the rest of the transport system as purely trace information.


Accordingly, the header field MUST NOT be included in the content covered by digital signatures.


11. Authentication-Results Definitions
11. 認証結果の定義

[AUTHRES] defines a mechanism for indicating, via a header field, the results of message authentication checks. Section 15 registers RRVS as a new method that can be reported in this way, as well as corresponding result names. The possible result names and their meanings are as follows:


none: The message had no recipient mailbox timestamp associated with it, either via the SMTP extension or header field method; this protocol was not in use.


unknown: At least one form of this protocol was in use, but continuous ownership of the recipient mailbox could not be determined.


temperror: At least one form of this protocol was in use, but some kind of error occurred during evaluation that was transient in nature; a later retry will likely produce a final result.


permerror: At least one form of this protocol was in use, but some kind of error occurred during evaluation that was not recoverable; a later retry will not likely produce a final result.


pass: At least one form of this protocol was in use, and the destination mailbox was confirmed to have been under continuous ownership since the timestamp thus provided.


fail: At least one form of this protocol was in use, and the destination mailbox was confirmed not to have been under continuous ownership since the timestamp thus provided.


Where multiple recipients are present on a message, multiple results can be reported using the mechanism described in [AUTHRES].


12. Examples
12. 例

In the following examples, "C:" indicates data sent by an SMTP client, and "S:" indicates responses by the SMTP server. Message content is CRLF terminated, though these are omitted here for ease of reading.


12.1. SMTP Extension Example
12.1. SMTP拡張の例
     C: [connection established]
     S: 220 ESMTP ready
     C: EHLO
     S: 250 RRVS
     C: MAIL FROM:<>
     S: 250 OK
     C: RCPT TO:<> RRVS=2014-04-03T23:01:00Z
     S: 550 5.7.17 is no longer valid
     C: QUIT
     S: 221 So long!
12.2. Header Field Example
12.2. ヘッダーフィールドの例
     C: [connection established]
     S: 220 ESMTP ready
     C: HELO
     S: 250
     C: MAIL FROM:<>
     S: 250 OK
     C: RCPT TO:<>
     S: 250 OK
     C: DATA
     S: 354 Ready for message content
     C: From: Mister Sender <>
        To: Miss Receiver <>
        Subject: Are you still there?
        Date: Fri, 28 Jun 2013 18:01:01 +0200
          Sat, 1 Jun 2013 09:23:01 -0700
        Are you still there?
     S: 550 5.7.17 is no longer valid
     C: QUIT
     S: 221 So long!
12.3. Authentication-Results Example
12.3. 認証結果の例

Here is an example use of the Authentication-Results header field used to yield the results of an RRVS evaluation:


     Authentication-Results:; rrvs=pass

This indicates that the message arrived addressed to the mailbox, the continuous ownership test was applied with the provided timestamp, and the check revealed that the test was satisfied. The timestamp is not revealed.


13. Security Considerations
13. セキュリティに関する考慮事項
13.1. Abuse Countermeasures
13.1. 虐待対策

The response of a server implementing this protocol can disclose information about the age of an existing email mailbox. Implementation of countermeasures against probing attacks is RECOMMENDED. For example, an operator could track appearance of this field with respect to a particular mailbox and observe the timestamps being submitted for testing; if it appears that a variety of timestamps are being tried against a single mailbox in short order, the field could be ignored and the message silently discarded. This concern is discussed further in Section 14.


13.2. Suggested Use Restrictions
13.2. 推奨される使用制限

If the mailbox named in the field is known to have had only a single continuous owner since creation, or not to have existed at all (under any owner) prior to the date-time specified in the field, then the field SHOULD be silently ignored and normal message handling applied so that this information is not disclosed. Such fields are likely the product of either gross error or an attack.


A message author using this specification might restrict inclusion of the header field such that it is only done for recipients known also to implement this specification, in order to reduce the possibility of revealing information about the relationship between the author and the mailbox.


If ownership of an entire domain is transferred, the new owner may not know what addresses were assigned in the past by the prior owner. Hence, no address can be known not to have had a single owner, or to have existed (or not) at all. In this case, the "unknown" result is likely appropriate.


13.3. False Sense of Security
13.3. 誤った安心感

Senders implementing this protocol likely believe their content is being protected by doing so. It has to be considered, however, that receiving systems might not implement this protocol correctly, or at all. Furthermore, use of RRVS by a sending system constitutes nothing more than a request to the receiving system; that system could choose not to prevent delivery for some local policy, for legal or operational reasons, which compromises the security the sending system believed was a benefit to using RRVS. This could mean the timestamp information involved in the protocol becomes inadvertently revealed.


This concern lends further support to the notion that senders would do well to avoid using this protocol other than when sending to known, trusted receivers.


13.4. Reassignment of Mailboxes
13.4. メールボックスの再割り当て

This specification is a direct response to the risks involved with reassignment or recycling of email addresses, an inherently dangerous practice. It is typically expected that email addresses will not have a high rate of turnover or ownership change.


It is RECOMMENDED to have a substantial period of time between mailbox owners during which the mailbox accepts no mail, giving message generators an opportunity to detect that the previous owner is no longer at that address.


14. Privacy Considerations
14. プライバシーに関する考慮事項
14.1. The Tradeoff
14.1. トレードオフ

That some MSPs allow for expiration of account names when they have been unused for a protracted period forces a choice between two potential types of privacy vulnerabilities, one of which presents significantly greater threats to users than the other. Automatically generated mail is often used to convey authentication credentials that can potentially provide access to extremely sensitive information. Supplying such credentials to the wrong party after a mailbox ownership change could allow the previous owner's data to be exposed without his or her authorization or knowledge. In contrast, the information that may be exposed to a third party via the proposal in this document is limited to information about the mailbox history. Given that MSPs have chosen to allow transfers of mailbox ownership without the prior owner's involvement, the information leakage from the extensions specified here creates far lower overall risk than the potential for delivering mail to the wrong party.

一部のMSPは、長期間使用されていないアカウント名の有効期限を許可するため、2つの潜在的なプライバシーの脆弱性から1つを選択する必要があり、一方はユーザーに対して他方よりもはるかに大きな脅威を提示します。自動生成されたメールは、非常に機密性の高い情報へのアクセスを提供する可能性のある認証資格情報を伝えるためによく使用されます。メールボックスの所有権が変更された後、このような資格情報を間違った当事者に提供すると、前の所有者のデータが許可や知識なしに公開される可能性があります。対照的に、このドキュメントの提案を通じて第三者に公開される可能性のある情報は、メールボックスの履歴に関する情報に限定されます。 MSPが以前の所有者の関与なしにメールボックスの所有権の転送を許可することを選択した場合、ここで指定された拡張機能からの情報漏えいは、間違った相手にメールを配信する可能性よりも全体的なリスクがはるかに低くなります。

14.2. Probing Attacks
14.2. 攻撃の調査

As described above, use of this extension or header field in probing attacks can disclose information about the history of the mailbox. The harm that can be done by leaking any kind of private information is difficult to predict, so it is prudent to be sensitive to this sort of disclosure, either inadvertently or in response to probing by an attacker. It bears restating, then, that implementing countermeasures against abuse of this capability needs strong consideration.


14.3. Envelope Recipients
14.3. エンベロープ受信者

The email To and Cc header fields are not required to be populated with addresses that match the envelope recipient set, and Cc may even be absent. However, the algorithm in Section 3 requires that this header field contain a match for an envelope recipient in order to be actionable. As such, use of this specification can reveal some or all of the original intended recipient set to any party that can see the message in transit or upon delivery.


For a message destined to a single recipient, this is unlikely to be a concern, which is one of the reasons use of this specification on multi-recipient messages is discouraged.


14.4. Risks with Use
14.4. 使用に伴うリスク

MDAs might not implement the recommendation to remove the header field defined here when messages are delivered, either out of ignorance or due to error. Since user agents often do not render all of the header fields present, the message could be forwarded to another party that would then inadvertently have the content of this header field.


A bad actor may detect use of either form of the RRVS protocol and interpret it as an indication of high-value content.


15. IANA Considerations
15. IANAに関する考慮事項
15.1. SMTP Extension Registration
15.1. SMTP拡張機能の登録

Section 2.2.2 of [SMTP] sets out the procedure for registering a new SMTP extension. IANA has registered the SMTP extension using the details provided in Section 3.1 of this document.

[SMTP]のセクション2.2.2は、新しいSMTP拡張機能を登録する手順を示しています。 IANAは、このドキュメントのセクション3.1に記載されている詳細を使用して、SMTP拡張機能を登録しました。

15.2. Header Field Registration
15.2. ヘッダーフィールドの登録

IANA has added the following entry to the "Permanent Message Header Field Names" registry, as per the procedure found in [IANA-HEADERS]:

[IANA-HEADERS]にある手順に従って、IANAは次のエントリを「Permanent Message Header Field Names」レジストリに追加しました。

Header field name: Require-Recipient-Valid-Since Applicable protocol: mail ([MAIL]) Status: standard Author/Change controller: IETF Specification document(s): RFC 7293 Related information: Requesting review of any proposed changes and additions to this field is recommended.

ヘッダーフィールド名:Require-Recipient-Valid-Since該当プロトコル:メール([MAIL])ステータス:標準の作成者/変更コントローラー:IETF仕様ドキュメント:RFC 7293関連情報:提案された変更とこれへの追加のレビューの要求フィールドをお勧めします。

15.3. Enhanced Status Code Registration
15.3. 強化されたステータスコード登録

IANA has registered the following in the Enumerated Status Codes table of the "Simple Mail Transfer Protocol (SMTP) Enhanced Status Codes Registry":

IANAは、「Simple Mail Transfer Protocol(SMTP)Enhanced Status Codes Registry」のEnumerated Status Codesテーブルに以下を登録しています。

Code: X.7.17 Sample Text: Mailbox owner has changed Associated basic status code: 5XX Description: This status code is returned when a message is received with a Require-Recipient-Valid-Since field or RRVS extension and the receiving system is able to determine that the intended recipient mailbox has not been under continuous ownership since the specified date-time. Reference: RFC 7293 Submitter: M. Kucherawy Change controller: IESG

コード:X.7.17サンプルテキスト:メールボックスの所有者が変更されました関連する基本ステータスコード:5XX説明:このステータスコードは、メッセージがRequire-Recipient-Valid-SinceフィールドまたはRRVS拡張で受信され、受信システムが次のことができる場合に返されます指定された日時以降、対象の受信者のメールボックスが継続的な所有権を持っていないことを確認します。参照:RFC 7293提出者:M. Kucherawy変更コントローラー:IESG

Code: X.7.18 Sample Text: Domain owner has changed Associated basic status code: 5XX Description: This status code is returned when a message is received with a Require-Recipient-Valid-Since field or RRVS extension and the receiving system wishes to disclose that the owner of the domain name of the recipient has changed since the specified date-time. Reference: RFC 7293 Submitter: M. Kucherawy Change controller: IESG

コード:X.7.18サンプルテキスト:ドメインの所有者が変更されました関連する基本ステータスコード:5XX説明:このステータスコードは、Require-Recipient-Valid-SinceフィールドまたはRRVS拡張でメッセージを受信し、受信側システムが開示したい場合に返されます受信者のドメイン名の所有者が指定された日時以降に変更されたこと。参照:RFC 7293提出者:M. Kucherawy変更コントローラー:IESG

Code: X.7.19 Sample Text: RRVS test cannot be completed Associated basic status code: 5XX Description: This status code is returned when a message is received with a Require-Recipient-Valid-Since field or RRVS extension and the receiving system cannot complete the requested evaluation because the required timestamp was not recorded. The message originator needs to decide whether to reissue the message without RRVS protection. Reference: RFC 7293 Submitter: M. Kucherawy Change controller: IESG

コード:X.7.19サンプルテキスト:RRVSテストを完了できません関連する基本ステータスコード:5XX説明:このステータスコードは、メッセージがRequire-Recipient-Valid-SinceフィールドまたはRRVS拡張で受信され、受信側システムが完了できない場合に返されます必要なタイムスタンプが記録されなかったため、要求された評価。メッセージの発信者は、RRVS保護なしでメッセージを再発行するかどうかを決定する必要があります。参照:RFC 7293提出者:M. Kucherawy変更コントローラー:IESG

15.4. Authentication Results Registration
15.4. 認証結果の登録

IANA has registered the following in the "Email Authentication Methods" registry:

IANAは、「Email Authentication Methods」レジストリに以下を登録しています。

Method: rrvs


Specifying Document: RFC 7293

ドキュメントの指定:RFC 7293

ptype: smtp


Property: rcptto


Value: envelope recipient


Status: active


Version: 1


IANA has also registered the following in the "Email Authentication Result Names" registry:

IANAはまた、「Email Authentication Result Names」レジストリに以下を登録しています。

Codes: none, unknown, temperror, permerror, pass, fail


Defined: RFC 7293

定義済み:RFC 7293

Auth Method(s): rrvs


Meaning: Section 11 of RFC 7293

意味:RFC 7293のセクション11

Status: active


16. Acknowledgments
16. 謝辞

Erling Ellingsen proposed the idea.

Erling Ellingsenさんがアイデアを提案しました。

Reviews and comments were provided by Michael Adkins, Kurt Andersen, Eric Burger, Alissa Cooper, Dave Cridland, Dave Crocker, Ned Freed, John Levine, Alexey Melnikov, Jay Nancarrow, Hector Santos, Gregg Stefancik, and Ed Zayas.

レビューとコメントは、Michael Adkins、Kurt Andersen、Eric Burger、Alissa Cooper、Dave Cridland、Dave Crocker、Ned Freed、John Levine、Alexey Melnikov、Jay Nancarrow、Hector Santos、Gregg Stefancik、およびEd Zayasから提供されました。

17. References
17. 参考文献
17.1. Normative References
17.1. 引用文献

[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.

[ABNF] Crocker、D。およびP. Overell、「構文仕様の拡張BNF:ABNF」、STD 68、RFC 5234、2008年1月。

[DATETIME] Klyne, G., Ed. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, July 2002.

[日時]クライン、G、エド。 C.ニューマン、「インターネット上の日付と時刻:タイムスタンプ」、RFC 3339、2002年7月。

[IANA-HEADERS] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004.

[IANA-HEADERS] Klyne、G.、Nottingham、M.、J。Mogul、「Registration Procedures for Message Header Fields」、BCP 90、RFC 3864、2004年9月。

[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

[キーワード] Bradner、S。、「RFCで使用して要件レベルを示すためのキーワード」、BCP 14、RFC 2119、1997年3月。

[MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322, October 2008.

[メール] Resnick、P。、編、「インターネットメッセージ形式」、RFC 5322、2008年10月。

[NTP] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, June 2010.

[NTP] Mills、D.、Martin、J.、Burbank、J。、およびW. Kasch、「Network Time Protocol Version 4:Protocol and Algorithms Specification」、RFC 5905、2010年6月。

[ROLES] Crocker, D., "Mailbox Names for Common Services, Roles and Functions", RFC 2142, May 1997.

[役割] Crocker、D。、「Common Services、Roles and Functionsのメールボックス名」、RFC 2142、1997年5月。

[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, October 2008.

[SMTP] Klensin、J。、「Simple Mail Transfer Protocol」、RFC 5321、2008年10月。

17.2. Informative References
17.2. 参考引用

[AUTHRES] Kucherawy, M., "Message Header Field for Indicating Message Authentication Status", RFC 7001, September 2013.

[AUTHRES] Kucherawy、M。、「メッセージ認証ステータスを示すためのメッセージヘッダーフィールド」、RFC 7001、2013年9月。

[DSN] Moore, K. and G. Vaudreuil, "An Extensible Message Format for Delivery Status Notifications", RFC 3464, January 2003.

[DSN] Moore、K。およびG. Vaudreuil、「An Extensible Message Format for Delivery Status Notifications」、RFC 3464、2003年1月。

[DSN-SMTP] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)", RFC 3461, January 2003.

[DSN-SMTP] Moore、K。、「Simple Mail Transfer Protocol(SMTP)Service Extension for Delivery Status Notifications(DSNs)」、RFC 3461、2003年1月。

[EMAIL-ARCH] Crocker, D., "Internet Mail Architecture", RFC 5598, July 2009.

[メールアーク]クロッカーD.、「インターネットメールアーキテクチャ」、RFC 5598、2009年7月。

[ESC] Vaudreuil, G., "Enhanced Mail System Status Codes", RFC 3463, January 2003.

[ESC] Vaudreuil、G。、「Enhanced Mail System Status Codes」、RFC 3463、2003年1月。

Authors' Addresses


William J. Mills Yahoo! Inc.



Murray S. Kucherawy Facebook, Inc. 1 Hacker Way Menlo Park, CA 94025 USA

Murray S. Kucherawy Facebook、Inc. 1 Hacker Way Menlo Park、CA 94025 USA