Internet Draft K. Murchison Document: draft-murchison-lmtp-ignorequota-02.txt L. Greenfield Expires December 15, 2002 10 June 2002 LMTP Service Extension for Ignoring Recipient Quotas Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 To view the list Internet-Draft Shadow Directories, see http://www.ietf.org/shadow.html. Distribution of this memo is unlimited. Abstract This memo defines an extension to the LMTP service whereby a client may ask the server to ignore a recipient's quotas when delivering a message. Conventions Used in the Document In examples, "C:" and "S:" indicate lines sent by the client and 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 [KEYWORDS]. Expires December 15, 2002 Murchison [Page 1] Internet Draft LMTP Ignore Quota June 10, 2002 0. Meta-information on this draft This information is intended to facilitate discussion. It will be removed when this document leaves the Internet-Draft stage. 0.1. Discussion This draft is intended to be an extension to the Local Mail Transfer Protocol, available from the RFC repository as . A revised version of this draft document will be submitted to the RFC editor as Informational for the Internet Community. This draft and the Local Mail Protocol Extension itself are being discussed on the SMTP Extensions mailing list at . Subscription requests can be sent to (send an email message with the word "subscribe" in the body). More information on the mailing list along with a WWW archive of back messages is available at . 0.2. Noted Changes 0.2.1 since -01 Editorial changes (re-submission). 0.2.2 since -00 Editorial changes. 1. Introduction In many cases, the [LMTP] protocol is used to transfer messages to a delivery agent which might impose some limits on the usage of system resources by individual recipients (e.g. disk space on a mailstore). Sometimes it may be desirable for an LMTP client to inject a message into the mailstore regardless of these quotas (e.g. an automated process notifying users that they are over quota). This memo uses the mechanism defined in [ESMTP] to define an extension to the LMTP service whereby a client may ask a server to ignore such quotas when delivering a message. Expires December 15, 2002 Murchison [Page 2] Internet Draft LMTP Ignore Quota June 10, 2002 2. Framework for the Ignore Quota Extension The following service extension is hereby defined: (1) the name of the LMTP service extension is "Ignore Quota"; (2) the LHLO keyword value associated with this extension is "IGNOREQUOTA"; (3) no parameters are allowed with this LHLO keyword value; (4) one optional parameter using the keyword "IGNOREQUOTA" is added to the RCPT TO command; (5) the maximum length of a RCPT TO command line is increased by 12 characters by the possible addition of the IGNOREQUOTA keyword; (6) no additional LMTP verbs are defined by this extension. The remainder of this memo specifies how support for the extension affects the behavior of an LMTP client and server. 3. The Ignore Quota service extension When an LMTP client wishes to force delivery of a message regardless of quotas, it first issues the LHLO command to the server. If the LMTP server responds with code 250 to the LHLO command, and the response includes the LHLO keyword IGNOREQUOTA, then the server supˇ ports the Ignore Quota extension and will accept the extended verˇ sion of the RCPT command. The extended RCPT command is issued by an LMTP client when it wishes to have the server ignore the recipient's quotas. The extended RCPT command is identical to the RCPT command defined in [SMTP], except that an IGNOREQUOTA parameter must appear after the address. The complete syntax of this extended command is defined in [ESMTP], with the esmtp-keyword of IGNOREQUOTA. 4. Usage Example The following dialogue illustrates the use of the Ignore Quota serˇ vice extension: Expires December 15, 2002 Murchison [Page 3] Internet Draft LMTP Ignore Quota June 10, 2002 S: C: S: 220 foo.oceana.com LMTP Cyrus v2.0.11 ready C: LHLO oceana.com S: 250-foo.oceana.com S: 250-IGNOREQUOTA S: 250-8BITMIME S: 250-ENHANCEDSTATUSCODES S: 250-AUTH DIGEST-MD5 CRAM-MD5 EXTERNAL S: 250 PIPELINING C: MAIL FROM: S: 250 2.1.0 ok C: RCPT TO: S: 250 2.1.5 ok C: DATA S: 354 go ahead ... C: . S: 452 4.2.2 Over quota C: MAIL FROM: S: 250 2.1.0 ok C: RCPT TO: IGNOREQUOTA S: 250 2.1.5 ok C: DATA S: 354 go ahead ... C: . S: 250 2.1.5 Ok C: QUIT S: 221 2.0.0 bye 5. Security Considerations The Ignore Quota extension described in this memo can conceivably be used to force any or all users over their quotas and prevent further messages from being delivered. For this reason, implementations SHOULD try to limit the use of this extension to privileged or trusted users. Possible means for doing so would be to either authenticate and identify the user of the LMTP client by using the mechanism defined in [SMTPAUTH] or restrict the use of the LMTP client via permissions or access control lists. Expires December 15, 2002 Murchison [Page 4] Internet Draft LMTP Ignore Quota June 10, 2002 6. IANA Considerations The registration of the LMTP "IGNOREQUOTA" extension follows: Service Extension: Ignore Quota LHLO Keyword: IGNOREQUOTA Parameters: none Verb: none Added Behavior: defined in this memo 7. References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", Harvard University, RFC 2119, March 1997. [LMTP] Myers, J., "Local Mail Transfer Protocol", Carnegie-Mellon University, RFC 2033, October 1996. [SMTP] Klensin, J., Ed., "Simple Mail Transfer Protocol", AT&T Labˇ oratories, RFC 2821, April 2001. [ESMTP] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. Crocker, "SMTP Service Extensions", MCI, Innosoft Internaˇ tional, Inc., Dover Beach Consulting, Inc., Network Management Associates, Inc., Brandenburg Consulting, RFC 1869, November 1995. [SMTPAUTH] Myers, J., "SMTP Service Extension for Authentication", Netscape Communications, RFC 2554, March 1999. 8. Author's Address Kenneth Murchison Oceana Matrix Ltd. 21 Princeton Place Orchard Park, NY 14127 Phone: (716) 662-8973 EMail: ken@oceana.com Expires December 15, 2002 Murchison [Page 5] Internet Draft LMTP Ignore Quota June 10, 2002 Lawrence E. Greenfield Carnegie Mellon University 5000 Forbes Ave. Pittsburgh, PA 15213 Phone: (412) 268-4646 EMail: leg+@andrew.cmu.edu Expires December 15, 2002 Murchison [Page 6]