Lemonade Internet Draft: Lemonade Profile S. H. Maes Document: draft-ietf-lemonade-profile-02.txt A. Melnikov Expires: October 2005 April 2005 Lemonade Profile Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document describes a profile (a set of required extensions, restrictions and usage modes) of mail protocols such as IMAP and Submission. This profile allows clients (especially those that are constrained in memory, bandwidth, processing power, or other areas) to efficiently use IMAP and Submission to access and submit mail. This includes the ability to forward received mail without needing to download and upload the mail, to schedule future delivery of a message, to optimize submission and to efficiently reconnect in case of loss of connectivity with the server. The Lemonade profile relies upon extensions to various protocols; specifically URLAUTH, CATENATE, Lemonade Command Extensions in the IMAP protocol [RFC3501] and BURL in the SUBMIT protocol [RFC2476]. Maes Expires - October 2005 [Page 1] April 2005 In addition, the Lemonade profile contains Lemonade Command extensions for quick reconnect and media conversion. Conventions used in this document In examples, "M:", "I:" and "S:" indicate lines sent by the client messaging user agent, IMAP e-mail server and SMTP submit server respectively. 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 [RFC2119]. Table of Contents Status of this Memo ........................................ 1 Abstract.................................................... 1 Conventions used in this document........................... 2 Table of Contents........................................... 2 1. Introduction............................................. 3 2. Forward without download ................................ 3 2.1. Motivations ........................................ 3 2.2. Message Sending Overview............................ 3 2.3. Traditional Strategy................................ 4 2.4. Step by step description............................ 5 2.5. Normative statements related to forward without download ........................................... 8 2.6. Additional Considerations........................... 8 2.7. The fcc problem..................................... 9 3. Message Submission....................................... 9 3.1. Future Delivery..................................... 9 3.2. Pipelining..........................................10 3.3. TLS.................................................10 3.4. DSN Support ........................................11 3.5. Message size declaration............................11 4. Quick Reconnect scheme...................................11 4.1. Normative statements related to quick reconnect schemes ........................................... 12 5. Future work............................................. 12 Security Considerations.................................... 13 IANA Considerations ....................................... 13 References................................................. 13 Version History............................................ 14 Acknowledgments............................................ 15 Authors Addresses.......................................... 15 Intellectual Property Statement............................ 15 Full Copyright Statement................................... 16 Maes Expires - October 2005 [Page 2] April 2005 1. Introduction Lemonade provides enhancements to Internet email to support diverse service environments. This document describes the lemonade profile that includes: - The Lemonade Pull Model that describes exchanges between Lemonade Agents to allow clients to submit new email messages incorporating content which resides on locations external to the client and allow forward without download. - Media conversion - Quick reconnect The organization of this document is as follows. Section 2 describes the Lemonade Pull Model. Section 3 Section 3 describes the Media Conversion. Section 4 describes quick reconnect 2. Forward without download 2.1. Motivations The advent of client/server email using the [RFC3501] and [RFC2821] protocols has changed what formerly were local disk operations to become excessive and repetitive network data transmissions. The Lemonade Pull Model makes use of the [BURL] SUBMIT extension to enable access to external sources during the submission of a message. In combination with the IMAP [URLAUTH] extension, inclusion of message parts or even entire messages from the IMAP mail store is possible with a minimal trust relationship between the IMAP and SMTP SUBMIT servers. Pull has the advantage of maintaining one submission protocol, and thus avoids the risk of having multiple parallel and possible divergent mechanisms for submission. Furthermore, by keeping the details of message submission in the SMTP SUBMIT server, the Lemonade Pull Model can work with other message retrieval protocols such as POP, NNTP, or whatever else may be designed in the future. 2.2. Message Sending Overview The act of sending an email message is best thought of as involving multiple steps: initiation of a new draft, draft editing, message assembly, and message submission. Initiation of a new draft and draft editing takes place on the MUA. Frequently, users choose to save more complex messages on an [RFC3501] server (via the APPEND command with the \Draft flag) for later recall by the MUA and resumption of the editing process. Maes Expires - October 2005 [Page 3] April 2005 Message assembly is the process of producing a complete message from the final revision of the draft and external sources. At assembly time, external data is retrieved and inserted in the message. Message submission is the process of inserting the assembled message into the [RFC2821] infrastructure, typically using the [RFC2476] protocol. 2.3. Traditional Strategy Traditionally, messages are initiated, edited, and assembled entirely within an MUA, although drafts may be saved to an [RFC3501] server and later retrieved from the server. The completed text is then transmitted to an MSA for delivery. There is often no clear boundary between the editing and assembly process. If a message is forwarded, its content is often retrieved immediately and inserted into the message text. Similarly, once external content is inserted or attached, the content is usually retrieved immediately and made part of the draft. As a consequence, each save of a draft and subsequent retrieve of the draft transmits that entire (possibly large) content, as does message submission. In the past, this was not much of a problem, because drafts, external data, and the message submission mechanism were typically located on the same system as the MUA. The most common problem was running out of disk quota. Maes Expires - October 2005 [Page 4] April 2005 2.4. Step by step description The model distinguishes between a Messaging User Agent (MUA), an IMAPv4Rev1 Server ([RFC3501]) and a SMTP submit server ([RFC2476]), as illustrated in Figure 1. +--------------------+ +--------------+ | | <------------ | | | MUA (M) | | IMAPv4 Rev1 | | | | Server | | | ------------> | (Server I) | +--------------------+ +--------------+ ^ | ^ | | | | | | | | | | | | | | | | | | | | | | | | v | | +--------------+ | |------------------------->| SMTP | | | Submit | |-----------------------------| Server | | (Server S) | +--------------+ Figure 1: Lemonade Pull Model The Lemonade Pull Model allows a Messaging User Agent to compose and forward an e-mail combining fragments that are located in an IMAP server, without having to download these fragments to the server. In the [BURL]/[CATENATE] variant of the pull strategy, messages are initially composed and edited within an MUA. The [CATENATE] extension to [RFC3501] is then used to upload the message to the IMAP server and assemble it, and finally a [URLAUTH] format URL is given to a [RFC2476] server with the [BURL] extension for submission. The flow involved to support such a use case consists of: M: {to I -- Optional} The client connectects to the IMAP server and IMAP Fetch of body structures and UIDs (See [RFC3501]) Example: M: A0051 FETCH 161 (UID BODYSTRUCTURE) Maes Expires - October 2005 [Page 5] April 2005 I: * 161 FETCH (UID 25627 BODYSTRUCTURE (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") "<960723163407.20117h@washington.example.net>" "Compiler diff" "BASE64" 4554 73) "MIXED")) I: A0051 OK completed M: {to I} The client invokes CATENATE (See [CATENATE] for details of the semantics and steps û this allows the MUA to create messages on the IMAP using new data combined with body structure already present on the IMAP server. <> M: A0052 CATENATE Sent FLAGS (\Seen $MDNSent) TEXT {738} I: + Ready for literal data M: Return-Path: M: Received: from [127.0.0.2] M: by rufus.example.org via TCP (internal) with ESMTPA; M: Thu, 11 Nov 2004 16:57:07 +0000 M: Message-ID: <419399E1.6000505@example.org> M: Date: Thu, 12 Nov 2004 16:57:05 +0000 M: From: Bob Ar M: X-Accept-Language: en-us, en M: MIME-Version: 1.0 M: To: foo@example.net M: Subject: About our holiday trip M: Content-Type: multipart/mixed; M: boundary="------------030308070208000400050907" M: M: --------------030308070208000400050907 M: Content-Type: text/plain; charset=us-ascii; format=flowed M: Content-Transfer-Encoding: 7bit M: M: Our travel agent has sent the updated schedule. M: M: Cheers, M: Bob M: --------------030308070208000400050907 M: URL "imap://imap.example.org/INBOX;UIDVALIDITY=385759045/; UID=25627;Section=1.2" TEXT {44} I: + Ready for literal data M: --------------030308070208000400050907-- M: I: A0052 OK [APPENDUID 387899045 45] CATENATE Completed Maes Expires - October 2005 [Page 6] April 2005 M: A0053 UID STORE XXX +FLAGS.SILENT ($Forwarded) I: A0053 OK STORE completed << EditorÆs note: Recommend UIDPLUS extension û especially useful when appending messages to a non-selected mailbox>> M: {to I} The client uses GENURLAUTH command to request and URLAUTH URL (See [URLAUTH]). I: {to M} The IMAP server returns URLAUTH URL suitable for later retrieval with URLFETCH (See [URLAUTH] for details of the semantics and steps). M: A0054 GENURLAUTH "imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;uid=45/;urla uth=submit+bar" INTERNAL I: * GENURLAUTH "imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;uid=45/;urla uth=submit+bar:internal:91354a473744909de610943775f92038" I: A0054 OK GENURLAUTH completed M: {to S} The client connects to the SMTP submission server and starts a new mail transaction. It uses BURL to let the SMTP submit server fetch the content of the message from the IMAP server (See [BURL] for details of the semantics and steps û this allows the MUA to authorize the SMTP submit server to access the message composed as a result of the CATENATE step). M: EHLO potter.example.org S: 250-owlry.example.com S: 250-8BITMIME S: 250-BURL imap S: 250-AUTH PLAIN S: 250-DSN S: 250 ENHANCEDSTATUSCODES M: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8= S: 235 2.7.0 PLAIN authentication successful. M: MAIL FROM: S: 250 2.5.0 Address Ok. M: RCPT TO: S: 250 2.1.5 ron@gryffindor.example.com OK. M: BURL imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;uid=45/;urlau th=submit+bar:internal:91354a473744909de610943775f92038 LAST S: {to I} The SMTP submission server uses URLFETCH to fetch the message to be sent (See [URLAUTH] for details of the semantics and steps. The so-called "pawn-ticket" authorization mechanism uses a URI which contains its own authorization credentials.). Maes Expires - October 2005 [Page 7] April 2005 I: {to S} Provides the message composed as a result of the CATENATE step). SMTP submission server opens IMAP connection to the IMAP server: I: * OK [CAPABILITY IMAP4REV1 URLAUTH] example.com IMAP server ready S: a001 LOGIN submitserver secret I: a001 OK submitserver logged in S: a002 URLFETCH " imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;uid=45/;urlau th=submit+bar:internal:91354a473744909de610943775f92038" I: * URLFETCH " imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;uid=45/;urlau th=submit+bar:internal:91354a473744909de610943775f92038" {15065} ...message body follows... S: a002 OK URLFETCH completed << EditorÆs note: The SMTP submission server may LOGOUT>> S2: {to M} OK (2XX) Submission server returns OK to the MUA: S: 250 2.5.0 Ok. 2.5. Normative statements related to forward without download Lemonade compliant mail server MUST therefore respectively support IMAPv4 Rev1 [RFC3501], CATENATE [CATENATE] and URLAUTH [URLAUTH]. Its support MUST be declared via CAPABILITY [RFC3501]. Lemonade compliant SMTP submit servers MUST support BURL extensions [BURL]. Its support MUST be declared via EHLO [RFC2821]. A Lemonade client SHOULD support IMAPv4 Rev1 [RFC3501], CATENATE [CATENATE], BURL extensions [BURL] and URLAUTH [URLAUTH]. Additional normative statements are provided in other sections. 2.6. Additional Considerations The so-called "pawn-ticket" authorization mechanism uses a URI which contains its own authorization credentials using [URLAUTH]. The advantage of this mechanism is that the SMTP submit [RFC2476] server can not access any data on the [RFC3501] server without a "pawn- ticket" created by the client. The "pawn-ticket" grants acces only to the specific data that the SMTP submit [RFC2476] server is authorized to access, can be revoked by the client, and can have a time-limited validity. Maes Expires - October 2005 [Page 8] April 2005 2.7. The fcc problem The "fcc problem" refers to a frequent need to deliver a copy of the message to a "file carbon copy" recipient. By far, the most common case of fcc is a client leaving a copy of outgoing mail in a "sent messages" or "outbox" mailbox. In the traditional strategy, the MUA duplicates the effort spent in transmitting to the MSA by writing the message to the fcc destination in a separate step. This may be a write to a local disk file or an APPEND to a mailbox on an IMAP server. The latter is one of the "excessive and repetitive network data transmissions" which represents the "problem" aspect of the "fcc problem". The [CATENATE] extension to [RFC3501] addresses the fcc problem. It requires making several simplifying assumptions: (1a) there is one, and only one, fcc destination on a single server (2a) the server which holds the fcc is the same as the server which stages the outgoing message for submission (3a) it is desired that the fcc be a copy of the complete message text with all external data inserted in the message << EditorÆs note: [POSTADDRESS] can be used to address issues (1a) and (2a). To be done later>> 3. Message Submission LEMONADE compliant SMTP submission server are expected to implement a set of SMTP extensions to make message submission efficient. The clients SHOULD take advantage of these features. 3.1. Future Delivery Diverse devices may suffer from intermittent or unpredictable connectivity. Although this does not address the main issues of intermittent connectivity, it may be of interest to email users to be able to take advantage of future delivery by marking ahead of time a message for future submission into the mail system. For well-connected devices, the client can hold a message in the conceptual "outbox" until an appointed time, and then release the message. Otherwise, the client may need to rely upon a well- connected server for this function. LEMONADE compliant SMTP submission servers MUST declare via ELHO [RFC2821] the support the SMTP service extension for future delivery. Maes Expires - October 2005 [Page 9] April 2005 If future delivery is not permitted by policy, the server MAY not support (and declare) support for future delivery or the SMTP submission server may advertise a future delivery interval of zero seconds. <> LEMONADE clients requiring the ability to reliably send future delivery messages can discover via EHLO if a lemonade SMTP submission server supports the SMTP service extension for future deliver [Future delivery]. When dealing with an device that support future delivery, such clients may cache or otherwise remember the advertised future delivery interval from a previous submission transaction to guide the human user into the selection of a valid future delivery interval. 3.2. Pipelining Mobile clients regularly use networks with a relatively high latency. Avoidance of round-trips within a transaction has a great advantage for the reduction in both bandwidth and total transaction time. For this reason Lemonade servers and clients should use SMTP command pipelining for message submission. LEMONADE compliant SMTP submission servers MUST support the SMTP Service Extensions for Command Pipelining. [REF2197] Clients SHOULD pipeline. 3.3. TLS LEMONADE clients may use the BURL extension to SMTP Submission, a protocol that requires sending a URLAUTH token to the SMTP submission server. Such a token should be protected from interception to avoid a replay attack that will disclose the contents of the message to an attacker. TLS based encryption of the SMTP submission path will provide protection against this attack. LEMONADE Compliant SMTP submission servers MUST support SMTP Service Extension for Secure SMTP over TLS [RFC2487] supporting at least SASL PLAIN [RFC2595] authentication. Maes Expires - October 2005 [Page 10] April 2005 LEMONADE clients SHOULD use TLS protected SMTP submission channels when using BURL-based message submission to protect the URLAUTH token from interception. 3.4. DSN Support It is expected that a LEMONADE compliant SMTP submission servers supports delivery status notifications. LEMONADE compliant SMTP submission servers MUST support SMTP service extensions for delivery status notifications [RFC3461] and enhanced status codes. <> 3.5. Message size declaration LEMONADE compliant SMTP submission servers MUST support the SMTP Service Extension for Message Size Declaration [RFC2927] 4. Quick Reconnect scheme Mobile operators usually charge users for the time their mobile client gets connected to the Internet and/or for the amount of information sent/received. Thus a mobile client should minimize time it stays connected to its mail server, which suggests that it should disconnect and reconnect frequently. Also, it is possible that the mobile client unexpectedly leaves area of connectivity, which will require that the client reconnects when connectivity returns. << EditorÆs note: Discussion about voluntarily versa non-voluntarily disconnects might go here>> IMAP can be verbose. Usually, in order to synchronize a client with a server after a disconnect, the client needs to issue at least the following commands: LOGIN/AUTHENTICATE, SELECT and several FETCH commands (see [IMAP-DISC] for more details). Thus, there is a desire to have a quick reconnect facility in IMAP, which will give a mobile client ability to resume a previously abandoned session, without the need to perform the full synchronization sequence as described above. Maes Expires - October 2005 [Page 11] April 2005 << EditorÆs note: Example is as per reconnect-02, syntax is subject to change>> S: * OK [CAPABILITY IMAP4REV1 STARTTLS AUTH=LOGIN CONDSTORE X-DRAFT-W02-RECONNECT] imap.example.com IMAP4rev1 2001.315rh at Thu, 15 Jul 2004 11:47:49 -0400 (EDT) C: b0002 authenticate login (SID P1234567890 56789 20010715194045000 41,43:211,214:541) S: + VXNlciBOYW1lAA== C: dGVzdDg= S: + UGFzc3dvcmQA C: dGVzdDg= S: * FOLDER INBOX S: * 464 EXISTS S: * 3 RECENT S: * OK [UIDVALIDITY 3857529045] UIDVALIDITY S: * OK [UIDNEXT 550] Predicted next UID S: * OK [HIGHESTMODSEQ 20010715194045007] S: * 1 FETCH (UID 1 FLAGS (\Seen)) S: b0002 OK [CAPABILITY IMAP4REV1 IDLE NAMESPACE MAILBOX-REFERRALS SCAN SORT THREAD=REFERENCES THREAD=ORDEREDSUBJECT MULTIAPPEND] User test8 authenticated 4.1. Normative statements related to quick reconnect schemes Lemonade compliant mail server MUST support the quick reconnect scheme described above. A Lemonade client SHOULD support the quick reconnect scheme described above. 5. Future work Future versions of the Lemonade profile are expected to address issues related to access of email form mobile devices, possibly including: - Address editorÆs notes - Recommendations in terms of support of Binary and 8-bit MIME Transport - Media conversion (static and streamed) - transport optimization for low or costly bandwidth and less reliable mobile networks - server to client notifications outside of the traditional IMAP band - dealing with firewall and intermediaries - compression Maes Expires - October 2005 [Page 12] April 2005 - filtering Security Considerations Security considerations on the Lemonade Pull Model are discussed throughout section 2. << EditorÆs note: TBD (Reconnect, etc.)>> IANA Considerations Lemonade profile extensions should be appropriately related to the list of IMAP and SMTP parameters. References [BURL] Newman, C. "Message Composition", draft-ietf-lemonade-burl- XX.txt (work in progress). [CATENATE]Resnick, P. "Internet Message Access Protocol (IMAP) CATENATE Extension", draft-ietf-lemonade-catenate-XX, (work in progress). [Future delivery] White, G. and Vaudreuil, G. "SMTP Submission Service Extension for Future Delivery", work in progress, draft- ietf-lemonade-futuredelivery-XX.txt [POSTADDRESS] Melnikov, A. "IMAP4 POSTADDRESS extension", work in progress, draft-melnikov-imap-postaddress-XX.txt [RECONNECT] Melnikov, A. and C. Wilson " IMAP4 extension for quick reconnect ", work in progress, draft-ietf-lemonade-reconnect- XX.txt [IMAP-DISC] Melnikov, A. "Synchronization Operations For Disconnected Imap4 Clients", IMAP-DISC, work in progress, draft- melnikov-imap-disc-XX.txt [RFC2119] Brader, S. "Keywords for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. http://www.ietf.org/rfc/rfc2119 [RFC2180] Gahrns, M. "IMAP4 Multi-Accessed Mailbox Practice", RFC 2180, July 1997. http://www.ietf.org/rfc/rfc2180 [RFC2197] Freed, N. "SMTP Service Extension for Command Pipelining", RFC 2197, September 1997. http://www.ietf.org/rfc/rfc2197 Maes Expires - October 2005 [Page 13] April 2005 [RFC2234] Crocker, D. and Overell, P. "Augmented BNF for Syntax Specifications", RFC 2234, Nov 1997. http://www.ietf.org/rfc/rfc2234 [RFC2476] Gellens, R. and Klensin, J., "Message Submission", RFC 2476, December 1998. http://www.ietf.org/rfc/rfc2476 [RFC2487] Hoffman, P. "SMTP Service Extension for Secure SMTP over TLS ", RFC 2487, Jan 1999. http://www.ietf.org/rfc/rfc2487 [RFC2595] Newman, C. "Using TLS with IMAP, POP3 and ACAP ", RFC 22595, Jun 1999. http://www.ietf.org/rfc/rfc2585 [RFC2683] Leiba, B. "IMAP4 Implementation Recommendations", RFC 2683 Sep 1999. http://www.ietf.org/rfc/rfc2683 [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [RFC2822] Resnick, P. "Internet Message Format", RFC 2822, April 2001. http://www.ietf.org/rfc/rfc2822 [RFC3501] Crispin, M. "IMAP4, Internet Message Access Protocol Version 4 rev1", RFC 3501, March 2003. http://www.ietf.org/rfc/rfc3501 [RFC3461] Gellens, R. and Klensin, J., "Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)", RFC 3461, January 2003. http://www.ietf.org/rfc/rfc3461 [URLAUTH] Crispin, M. and Newman, C., "Internet Message Access Protocol (IMAP) - URLAUTH Extension", draft-ietf-lemonade-urlauth- XX.txt, (work in progress). Version History Version 02: [1] Improved abstract based on review comments as well as change to reflect the re-organized content of the present Lemonade profile. [2] Editorial improvement of section 2.1 [3] Addition of section 2.5 with normative statements for lemonade compliant clients and servers regarding forward without download. [4] Addition of section 3 on message submission. [5] Move of media conversion to future work [6] Add section 4.1 on normative statements related to quick reconnect scheme. Maes Expires - October 2005 [Page 14] April 2005 [6] Addition of Binary and 8-bit MIME Transport to future work [7] Addition of IANA statement [8] Update and fix of the references Version 01: [1] We removed the sections of the profile related to mobile e-mail as well as discussion. This will be part of the next version of the Lemonade profile work. [2] We added detailed examples for the different steps included in section 2.4. [3] We added section 3 on media conversion [4] We added examples on Quick reconnect schemes in section 4. [5] We updated the security considerations [6] We fixed references based on updates above [7] We added a future work section [8] We fixed the boiler plate statements on the ôstatus of this memoö and ôCopyrightö. Acknowledgments This document is based on the work in progress described in draft- crispin-lemonade-pull-xx.txt. Authors Addresses Stephane H. Maes Oracle Corporation 500 Oracle Parkway M/S 4op634 Redwood Shores, CA 94065 USA Phone: +1-650-607-6296 Email: stephane.maes@oracle.com Alexey Melnikov Isode Limited 5 Castle Business Village 36 Station Road Hampton, Middlesex TW12 2BX UK Email: Alexey.melnikov@isode.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in Maes Expires - October 2005 [Page 15] April 2005 this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be Maes Expires - October 2005 [Page 16] April 2005 followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. Maes Expires - October 2005 [Page 17]