Individual submission D. Crocker
Internet-Draft Brandenburg InternetWorking
Intended status: Standards Track M. Kucherawy
Expires: May 18, 2012 Cloudmark, Inc.
November 15, 2011
Indicating Email Handling States in Trace Fields
draft-kucherawy-received-state-00
Abstract
This memo registers a trace field clause for use in indicating
transitions between handling queues, including enacting inter-host
message transitions. This might include message quarantining,
mailing list moderation, timed delivery, or other similar causes.
Status of This Memo
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This Internet-Draft will expire on May 18, 2012.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. New Trace Clause . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Mail Parameters Additional-registered-clauses
Sub-Registry . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Mail Parameters Registered-states Sub-Registry . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Trace Field Examples . . . . . . . . . . . . . . . . . 6
A.1. Typical Delivery Without Obvious Delays . . . . . . . . . . 6
A.2. Delivery With Moderation . . . . . . . . . . . . . . . . . 6
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
[SMTP] defines the content of email message trace fields, commonly
the "Received" field. These are typically used to record an audit
trail of the path a message follows from origin to destination.
There are some cases where there may be large time gaps between trace
fields. Though this might be caused by transient delivery issues,
they might also be caused by policy decisions or special processing
regarding the content of the message or authorization of some
identity on the message. Common examples include message quarantines
(filters that delay relaying or delivery of a message pending manual
operator action), or mailing list moderation rules (mailing list
owner action required regarding mail from authors not subscribed to
those lists).
This memo registers a new optional clause that can be used in trace
fields to indicate that a message entered such a special processing
queue for some period. This allows analysis to reveal that the cause
for a time gap in trace fields was an imposed delay rather than one
caused by transient technical difficulties.
2. Keywords
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].
3. New Trace Clause
This memo creates a new trace field clause, called "state", which can
be used to indicate the nature of a delay imposed on relaying of a
message toward its recipient(s). It is followed by a single keyword
that provides that detail. The following keywords are defined in
this document; extensions may define other registered keywords (see
Section 4.2):
moderation: The message entered a hold pending mailing list
moderator action.
other: The message entered a hold for reasons not covered by other
keywords in this list, and not for transient technology issues.
timed: The message entered a hold in order to meet a requested
delivery window.
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quarantine: The message entered a hold pending operator action for
local policy reasons.
The ABNF for this clause:
State = "state" queue-state-keyword
queue-state-keyword = ( reg-state-keyword / unreg-state-keyword )
reg-state-keyword = ( "moderation" / "other" /
"quarantine" / "timed" /
additional-state-keyword )
additional-state-keyword = unstructured
; see "IANA Considerations" below
unreg-state-keyword = unstructured
; from [MAIL]
A transfer agent making use of this extension MAY also include header
field comments to provide additional information.
Use of this clause by transfer agents is OPTIONAL.
4. IANA Considerations
4.1. Mail Parameters Additional-registered-clauses Sub-Registry
This memo adds to the "Additional-registered-clauses" sub-registry of
the "Mail Parameters" registry, created by [SMTP], the following
entry:
Clause name: state
Description: Indicates special queue state entry
State Summary: state <state-name>
Reference: [this memo]
4.2. Mail Parameters Registered-states Sub-Registry
The "Mail Parameters" registry at IANA is updated by the creation of
the "Registered-states" sub-registry to contain valid state keywords
for use with this specification. Updates to this registry are
governed by the Specification Required rules of [IANA].
Registrations must include the following entries:
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Name: The name of the state keyword being defined or updated
Description: A brief description of the keyword's meaning
Specification: The specification document that defines the queue
state being registered
Use: One of "current" (the state keyword is in current use),
"deprecated" (the state keyword is in use but not recommended for
new implementations), or "historic" (the state keyword is no
longer in substantial current use).
The initial registration set is as follows:
+------------+---------------------------+---------------+---------+
| Name | Description | Specification | Use |
+------------+---------------------------+---------------+---------+
| moderation | Held for list moderation | [this memo] | current |
+------------+---------------------------+---------------+---------+
| other | Held for causes not | [this memo] | current |
| | covered by other | | |
| | registered state keywords | | |
+------------+---------------------------+---------------+---------+
| quarantine | Held for operator action | [this memo] | current |
| | due to content analysis | | |
| | or local policy | | |
+------------+---------------------------+---------------+---------+
| timed | Held to accommodate a | [this memo] | current |
| | specific requested | | |
| | delivery window | | |
+------------+---------------------------+---------------+---------+
5. Security Considerations
The use of this trace information can reveal hints as to local policy
that was in effect at the time of message handling.
6. Normative References
[IANA] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008.
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Appendix A. Trace Field Examples
This section includes a sample of the new trace field clause in use.
A.1. Typical Delivery Without Obvious Delays
Typical message delivery
Received: from newyork.example.com
(newyork.example.com [192.0.2.250])
by mail-router.example.net (8.11.6/8.11.6)
for <recipient@example.net>
with ESMTP id i7PK0sH7021929;
Fri, Feb 15 2002 17:19:22 -0800
Received: from internal.example.com
(internal.example.com [192.168.0.1])
by newyork.example.com (8.11.6/8.11.6)
for <recipient@example.net>
with ESMTP id i9MKZCRd064134;
Fri, Feb 15 2002 17:19:08 -0800
Example 1: Typical message delivery with no appreciable handling
delays; only Received fields shown
A.2. Delivery With Moderation
Message delivery after moderation
Received: from newyork.example.com
(newyork.example.com [192.0.2.250])
by mail-router.example.net (8.11.6/8.11.6)
for <recipient@example.net>
with ESMTP id i7PK0sH7021929;
Fri, Feb 15 2002 18:33:29 -0800
Received: from internal.example.com
(internal.example.com [192.168.0.1])
by newyork.example.com (8.11.6/8.11.6)
for <secret-list@example.com>
state moderation (sender not subscribed);
with ESMTP id i9MKZCRd064134;
Fri, Feb 15 2002 17:19:08 -0800
Example 2: Message held for moderation; only Received fields shown
The message passed from internal.example.com to newyork.example.com
intended for a mailing list hosted at the latter. For list
administrative reasons, the message is held there for moderation. It
is finally released over an hour later and passed to the next host.
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A comment after the state expression indicates the actual cause for
the administrative hold.
Appendix B. Acknowledgements
The author wishes to acknowledge the following for their review and
constructive criticism of this proposal: [TBD]
Authors' Addresses
D. Crocker
Brandenburg InternetWorking
675 Spruce Dr.
Sunnyvale 94086
USA
Phone: +1.408.246.8253
EMail: dcrocker@bbiw.net
URI: http://bbiw.net
Murray S. Kucherawy
Cloudmark, Inc.
128 King St., 2nd Floor
San Francisco, CA 94107
US
Phone: +1 415 946 3800
EMail: msk@cloudmark.com
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