Minimal FAX address format in Internet Mail
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 2304.
|Last updated||2013-03-02 (Latest revision 1998-01-08)|
|RFC stream||Internet Engineering Task Force (IETF)|
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|IESG||IESG state||RFC 2304 (Proposed Standard)|
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Network Working Group C. Allocchio INTERNET-DRAFT GARR-Italy Expires: June 1998 December 1997 Minimal FAX address format in Internet Mail (draft-ietf-fax-minaddrfax-00.txt) Status of this Memo This document is an Internet Draft. 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. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a ``working draft'' or ``work in progress.'' Please check the I-D abstract listing contained in each Internet Draft directory to learn the current status of this or any other Internet Draft. 1. Introduction Since the very first e-mail to fax gateway objects appeared, a number of different methods to specify a fax address as an e-mail address have been used by implementors. Two major objectives for this were - enable an e-mail user to send faxes from his/her e-mail interface; - enable some kind of ''fax over e-mail service'' transport, to reduce the costs of fax transmissions, and use the existing e-mail infrastructure. This memo describes the MINIMAL addressing method and standard extensions to encode FAX addresses in e-mail addresses, as required in reference . The opposite problem, i.e. to allow a traditional numeric-only fax device user to access the e-mail transport service, is not discussed here. All implementations supporting this FAX over e-mail address format MUST support as a minimum the specification described in this document. The generic complex case of converting the whole PSTN addressing in e-mail is out of scope in this minimal specification: there is some work in progress in the field, where also a number of standard optional extensions are being defined. In this document the formal definitions are described using ABNF syntax, as defined into . We will also use some of the "CORE DEFINITIONS" defined in "APPENDIX A - CORE" of that document. The exact meaning of the capitalised words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL" is defined in reference . 2. Minimal Fax address The "service-selector" defined in section 2 of reference  for the fax service is: service-selector = "FAX" The minimal addressing for the fax service also requires support for a "qualif-type1" element (see section 2 of reference ). This element is an OPTIONAL element of the fax address, but its support, when present, is REQUIRED: qualif-type1 = "/" t33-sep "=" sub-addr where t33-sep = "T33S" sub-addr = 1*( DIGIT ) Thus, the minimal specification of a fax in e-mail address is: fax-address = fax-mbox [ "/T33S=" sub-addr ] fax-mbox = "FAX=" global-phone Note: See section 4.1 in case multiple sub-addr per fax-mbox need to be specified. The minimal supported syntax for global-phone (as described in section 2.1 of reference ) is: global-phone = "+" 1*( DIGIT , written-sep ) written-sep = ( "-" / "." ) The use of other dialling schemas for PSTN numbers (like private numbering plans or local dialling conventions) is also allowed. However, this does not preclude nor remove the minimal compulsory requirement to support the "global-phone" syntax as defined above. Any non "global-phone" dialling schema MUST NOT use the leading "+" between the "=" sign and the dialling string. The "+" sign is strictly reserved for the standard "global-phone" syntax. Note: The specification of these different dialling schemas is out of scope for this minimal specification. User specification of PSTN e-mail addresses will be facilitated if they can insert these separators between dial elements like digits etc. For this reason we allow them in the syntax the written-sep element. Implementors' note: Use of the written-sep elements is allowed, but not recommended. Any occurences of written-sep elements in a pstn-mbox MUST be ignored by all conformant implementations. User Agents SHOULD remove written-sep elements before submitting messages to the Message Transport System. 2.2 Some examples of a minimal "fax-address" FAX=+3940226338 FAX=+12027653000/T33S=1387 FAX=+33-1-88335215 3. The e-mail address of the I-fax device: mta-I-fax An "I-fax device" has an e-mail address, or to be more exact, a name which enables a mail system to identify it on the e-mail global system. In Internet mail, this is the Right Hand Side (RHS) part of the address, i.e. the part on the right of the "@" sign. We will call this mta-I-fax mta-I-fax = domain For "domain" strings used in SMTP transmissions, the string MUST conform to the requirements of that standard's <domain> specifications ,  and their updates. For "domain" strings used in message content headers, the string MUST conform to the requirements of the relevant standards ,  and their updates. Note: in both cases, the standards permit use of "domain names" or "domain literals" in addresses. 4. The fax-email The complete structure used to transfer a minimal FAX address over the Internet e-mail transport system is called "fax-email". This object is an e-mail address which conforms to RFC822  (and its updates) "addr-spec" syntax, with some extra structure which allows the FAX number to be identified. fax-email = ["/"] fax-address ["/"] "@" mta-I-fax Implementors' note: The optional "/" characters can result from other mail transport services gateways, where it is also an optional element. Implementations MUST accept the optional slashes but SHOULD NOT generate them. Gateways are allowed to strip them off when converting to Internet mail addressing. 4.1 Multiple subaddresses In case a particular service requires multiple T.33 subaddresses, and these subaddresses need to be given on the same "fax-mbox", multiple "fax-email" elements will be used. Implementors' note: The UA could accept multiple subaddress elements for the same global-phone, but it must generate multiple "fax-mbox" elements when passing the message to the MTA. 4.2 Some examples of minimal "fax-email" FAXfirstname.lastname@example.org FAX=+12027653000/T33Semail@example.com /FAXfirstname.lastname@example.org 5. Conclusion This proposal creates a minimal standard encoding for FAX addresses within the global e-mail transport system. The proposal requires no changes to existing e-mail software. 6. Security Considerations This document specifies a means by which FAX addresses can be encoded into e-mail addresses. As routing of e-mail messages is determined by Domain Name System (DNS) information, a successful attack on this service could force the mail path via some particular gateway or message transfer agent where mail security can be affected by compromised software. There are several means by which an attacker might be able to deliver incorrect mail routing information to a client. These include: (a) compromise of a DNS server, (b) generating a counterfeit response to a client's DNS query, (c) returning incorrect "additional information" in response to an unrelated query. Clients SHOULD ensure that mail routing is based only on authoritative answers. Once DNS Security mechanisms  become more widely deployed, clients SHOULD employ those mechanisms to verify the authenticity and integrity of mail routing records. 7. Copyright "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. 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 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. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." 8. Author's Address Claudio Allocchio Sincrotrone Trieste SS 14 Km 163.5 Basovizza I 34012 Trieste Italy RFC822: Claudio.Allocchio@elettra.trieste.it X.400: C=it;A=garr;P=Trieste;O=Elettra; S=Allocchio;G=Claudio; Phone: +39 40 3758523 Fax: +39 40 3758565 9. References  RFC821 Simple Mail Transfer Protocol. J. Postel. (August 1982)  RFC822 Standard for the format of ARPA Internet text messages. D. Crocker. (August 1982)  RFC1123 Requirements for Internet hosts - application and support. R.T. Braden. (October 1989)  RFC1528 Principles of Operation for the TPC.INT Subdomain: Remote Printing -- Technical Procedures. C. Malamud & M. Rose. (October 1993)  RFC2065 Domain Name System Security Extensions. D. Eastlake, 3rd, C. Kaufman. (January 1997)  RFC2119 Key words for use in RFCs to Indicate Requirement Levels. S. Bradner (March 1997)  RFC2234 Augmented BNF for Syntax Specifications. D. Crocker, P. Overell (November 1997).  ITU F.401 - Message Handling Services: Naming and Addressing for Public Message Handling Service; recommendation F.401 (August 1992)  ITU F.423 - Message Handling Services: Intercommunication Between the Interpersonal Messaging Service and the Telefax Service; recommendation F.423 (August 1992)  ITU E.164 - Numbering plan for the ISDN era; recommendation E.164/I.331 (August 1991)  ITU T.33 - Facsimile routing utilizing the subaddress; recommendation T.33 (July, 1996)  ETSI I-ETS 300,380 - Universal Personal Telecommunication (UPT): Access Devices Dual Tone Multi Frequency (DTMF) sender for acoustical coupling to the microphone of a handset telephone (March 1995)  RFCxxxx (DRAFT-IETF-FAX-ADDRMINGEN-xx.TXT) Minimal PSTN address format in Internet Mail. C. Allocchio. (xxxx 199x)  RFCxxxx (DRAFT-KILLE-MIXER-RFC1327BIS-xx.TXT) MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME. S.E. Kille. (xxxx 199x)