INTERNET DRAFT Nov 1992 Postmaster Convention for X.400 Operations Sat Nov 14 21:58:15 CST 1992 C. Allan Cargille University of Wisconsin Allan.Cargille@cs.wisc.edu This draft document is being circulated for comment. If consensus is reached it may be submitted to the RFC editor as a Proposed Standard protocol specification, for use in X.400 in the Internet. Please send comments to the author, or to the IETF OSI X.400 Operations Working Group mailing list . The following text is required by the Internet-draft rules: 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. Abstract: Both RFC822 and 1173 (Host Requirements) require that the email address "postmaster" be supported at all hosts. This paper extends this concept to X.400 mail domains which have registered RFC1327 mapping rules (and therefore which appear to have normal RFC822-style addresses). Cargille Expires May 18, 1993 [Page 1] DRAFT X.400 Postmaster Convention Nov 1992 1. Postmaster Convention in RFC822 Operating a reliable, large-scale electronic mail (email) network requires cooperation between many mail managers and system administrators. As noted in RFC822 [1], often mail or system managers need to be able to contact a responsible person at a remote host without knowing any specific user name or address at that host. For that reason, both RFC822 and the Internet Host Requirements [2] require that the address "postmaster" be supported at every Internet host. 2. Postmaster Convention and X.400 However, RFC822 is not the only email protocol being used in the Internet. Some Internet sites are also running the X.400 (1984) email protocol [3]. In the near future, the 1988 X.400 protocol is also expected to be in use [4]. RFC1327 specifies how to map between X.400 and RFC822 addresses [5]. When mapping rules are used, addresses map cleanly between X.400 and RFC822. In fact, it is impossible to determine by inspecting the address whether the recipient is an RFC822 mail user or an X.400 mail user. A paper by Rob Hagens and Alf Hansen describes an X.400 community known as the "Global Open MHS Community" (GO-MHS) [6]. Many mail domains in the GO-MHS Community have registered RFC1327 mapping rules. Therefore, users in those domains have RFC822-style email addresses, and these email domains are a logical extension of the RFC822 Internet. It is impossible to tell by inspecting a user's address whether the user receives RFC822 mail or X.400 mail. Since these addresses appear to be standard RFC822 addresses, mail managers, mailing list managers, host administrators, and users expect to be able to simply send mail to "postmaster@domain" and having the message be delivered to a responsible party. When an RFC1327 mapping rule exists, the X.400 address elements corresponding to the left-hand-side "postmaster" are "Surname=Postmaster" (both 1984 and 1988) and "CommonName=Postmaster" (1988 only). However, neither the X.400 protocols, North America X.400 Implementor's Agreements [7], nor the European X.400 Implementor's Agreements [8] require that "Surname=Postmaster" and "CommonName=Postmaster" be supported. (Supporting these addresses is recommended in X.400 (1988)). For mapped X.400 domains which do not support the postmaster address(es), this means that an address such as "user@some.place.zz" might be valid, yet mail to the corresponding address "postmaster@some.place.zz" fails. This is frustrating for remote administrators and users, and can even prevent operational problems from being Cargille Expires May 18, 1993 [Page 2] DRAFT X.400 Postmaster Convention Nov 1992 communicated and resolved. In this case, the desired seamless integration of the Internet RFC822 mail world and the mapped X.400 domain has not been achieved. The X.400 mail managers participating in the Cosine MHS Project discussed this problem in a meeting in June 1992 [9]. The discussion recognized the need for supporting the postmaster address at any level of the address hierarchy where these are user addresses. However, in the end, the Cosine MHS Managers only recommended support of the postmaster address Surname and Common Name at all levels of the address hierarchy down to the Organization level--that is, only for addresses of the form C=xx; ADMD=someadmd; S=postmaster C=xx; ADMD=someadmd; O=org; S=postmaster C=xx; ADMD=someadmd; PRMD=someprmd; S=postmaster C=xx; ADMD=someadmd; PRMD=someprmd; O=org; S=postmaster While there is value in supporting postmaster addresses down to the Organization level, this does not solve the entire problem of consistent email management between the Internet RFC822 world and mapped X.400 mail domains. Specifically, there are cases where a user's RFC822-style address maps into an X.400 address containing attributes below Organization, such as Organizational Units. Again, RFC822 community members have no idea what the X.400 representation of the address is, nor should they need to know. However, they expect that if they can send mail to (for example) "user@some.place.zz", then they should also be able to mail "postmaster@some.place.zz". If they cannot, then the desired seamless integration of the X.400 and RFC822 mail worlds has not been realized, and the quality of service has broken down. 3. Proposed Solution To fully achieve the desired seamless integration of email domains for which RFC1327 mapping rules have been defined, the following convention must be followed, If there are any valid addresses of the form "user@domain", then the address "postmaster@domain" must also be valid. To express this in terms of X.400: For every X.400 domain for which an RFC1327 mapping rule exists, if any address of the form Surname=User; is a valid address, then the address Cargille Expires May 18, 1993 [Page 3] DRAFT X.400 Postmaster Convention Nov 1992 Surname=Postmaster; must also be a valid address. If the X.400 system is running X.400(1988), then the address CommonName=Postmaster; must also be supported. To remain consistent with RFC822, "Mail sent to that address is to be routed to a person responsible for the site's mail system or to a person with responsibility for general site operation." [10] 4. References [1] RFC822 [2] RFC1173 [3] X.400 (1984) [4] X.400 (1988) [5] RFC1327 [6] presently draft-ietf-x400ops-mgtdomains-ops-02.txt [7] NIST X.400 Implementors Agreements [8] EWOS X.400 Implementors Agreements [9] Minutes from June 1992 Cosine MHS Managers Meeting [10] RFC822, direct quote Cargille Expires May 18, 1993 [Page 4]