draft-ietf-sieve-spamtestbis-05.txt   rfc5235.txt 
SIEVE Email Filtering Working C. Daboo Network Working Group C. Daboo
Group July 13, 2006 Request for Comments: 5235 January 2008
Internet-Draft Obsoletes: 3685
Expires: January 14, 2007 Category: Standards Track
SIEVE Email Filtering: Spamtest and Virustest Extensions
draft-ietf-sieve-spamtestbis-05
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This Internet-Draft will expire on January 14, 2007. Sieve Email Filtering: Spamtest and Virustest Extensions
Copyright Notice Status of This Memo
Copyright (C) The Internet Society (2006). This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
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Abstract Abstract
The SIEVE email filtering language "spamtest", "spamtestplus" and The Sieve email filtering language "spamtest", "spamtestplus", and
"virustest" extensions permit users to use simple, portable commands "virustest" extensions permit users to use simple, portable commands
for spam and virus tests on email messages. Each extension provides for spam and virus tests on email messages. Each extension provides
a new test using matches against numeric "scores". It is the a new test using matches against numeric "scores". It is the
responsibility of the underlying SIEVE implementation to do the responsibility of the underlying Sieve implementation to do the
actual checks that result in proper input to the tests. actual checks that result in proper input to the tests.
Change History (to be removed prior to publication as an RFC)
Changes from -04:
1. Relaxed capability requirement so that both spamtest and
spamtestplus can be present.
2. Tweaked text describing spam numeric value ranges.
Changes from -03:
1. Clarified that there are two possible ways to test for not-spam.
2. Clarified that 'not tested for xxx' also implies 'SIEVE could not
determine whether a test was done or not'.
Changes from -02:
1. Changed formatting of tables.
2. Fixed missing 2119 definitions.
3. Moved reference to previous extension to informative.
4. Minor text improvements.
5. Fixed some single/double quote issues.
6. Reworded abstract, introduction and overview to use better SIEVE
terminology when describing tests, commands and results.
7. Remove "untested" string result from ":percent" test.
8. Allow ":count" match type to be used for tested/untested checks.
Changes from -01:
1. Changed ACAP reference to i18n-comparators draft.
2. Changed MUST in security section for virus checker updates to
plain must.
3. Return string "untested" when :percent is used and no test has
been done.
4. Remove MUST NOT for having both spamtestplus and spamtest
capabilities present, and instead make it a SHOULD NOT.
5. Add text to state that implementations MUST return an error if
spamtestplus is not present when :percent is used.
6. Tweak first para of security considerations to better reflect
reality of testing.
7. Syntax -> Usage.
8. Updated references to 3028bis and 3431bis.
Changes from -00:
1. Added description of how to check for untested when using
:percent.
2. Changed requires item to "spamtestplus".
3. Changed text describing which requires item needs to be present.
Changes from RFC3685:
1. Added ":percent" argument to spamtest.
Table of Contents Table of Contents
1. Introduction and Overview . . . . . . . . . . . . . . . . . . 4 1. Introduction and Overview .......................................2
2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2. Conventions Used in This Document ...............................2
3. SIEVE Extensions . . . . . . . . . . . . . . . . . . . . . . . 5 3. Sieve Extensions ................................................3
3.1. General Considerations . . . . . . . . . . . . . . . . . . 5 3.1. General Considerations .....................................3
3.2. Test spamtest . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Test spamtest ..............................................3
3.2.1. spamtest without :percent argument . . . . . . . . . . 6 3.2.1. spamtest without :percent Argument ..................4
3.2.2. spamtest with :percent argument . . . . . . . . . . . 7 3.2.2. spamtest with :percent Argument .....................5
3.3. Test virustest . . . . . . . . . . . . . . . . . . . . . . 9 3.3. Test virustest .............................................7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 11 4. Security Considerations .........................................9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 5. IANA Considerations .............................................9
5.1. spamtest registration . . . . . . . . . . . . . . . . . . 12 5.1. spamtest Registration ......................................9
5.2. virustest registration . . . . . . . . . . . . . . . . . . 12 5.2. virustest Registration ....................................10
5.3. spamtestplus registration . . . . . . . . . . . . . . . . 13 5.3. spamtestplus Registration .................................10
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 6. References .....................................................10
6.1. Normative References . . . . . . . . . . . . . . . . . . . 13 6.1. Normative References ......................................10
6.2. Informative References . . . . . . . . . . . . . . . . . . 13 6.2. Informative References ....................................11
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 14 Appendix A. Acknowledgments .......................................12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Appendix B. Important Changes since RFC 3685 ......................12
Intellectual Property and Copyright Statements . . . . . . . . . . 16
1. Introduction and Overview 1. Introduction and Overview
SIEVE scripts are frequently being used to do spam and virus Sieve scripts are frequently being used to do spam and virus
filtering based on either implicit script tests (e.g. tests for filtering either based on implicit script tests (e.g., tests for
"black-listed" senders directly encoded in the SIEVE script), or via "black-listed" senders directly encoded in the Sieve script), or via
testing messages modified by some external spam or virus checker that testing messages modified by some external spam or virus checker that
handled the message prior to SIEVE. The use of third-party spam and handled the message prior to Sieve. The use of third-party spam and
virus checker tools poses a problem since each tool has its own way virus checker tools poses a problem since each tool has its own way
of indicating the result of its checks. These usually take the form of indicating the result of its checks. These usually take the form
of a header added to the message, the content of which indicates the of a header added to the message, the content of which indicates the
status using some syntax defined by the particular tool. Each user status using some syntax defined by the particular tool. Each user
has to then create their own SIEVE scripts to match the contents of has to then create their own Sieve scripts to match the contents of
these headers to do filtering. This requires the script to stay in these headers to do filtering. This requires the script to stay in
synchronization with the third party tool as it gets updated or synchronization with the third-party tool as it gets updated or
perhaps replaced with another. Thus scripts become tied to specific perhaps replaced with another. Thus, scripts become tied to specific
environments, and lose portability. environments and lose portability.
The purpose of this document is to introduce two SIEVE tests that can The purpose of this document is to introduce two Sieve tests that can
be used to implement "generic" tests for spam and viruses in messages be used to implement "generic" tests for spam and viruses in messages
processed via SIEVE scripts. The spam and virus checks themselves processed via Sieve scripts. The spam and virus checks themselves
are handled by the underlying SIEVE implementation in whatever manner are handled by the underlying Sieve implementation in whatever manner
is appropriate, so that the SIEVE spam and virus test commands can be is appropriate, so that the Sieve spam and virus test commands can be
used in a portable way. used in a portable way.
In order to do numeric comparisons against the returned strings, In order to do numeric comparisons against the returned strings,
server implementations MUST also support the SIEVE relational server implementations MUST also support the Sieve relational
[I-D.ietf-sieve-3431bis] extension, in addition to the extensions [RFC5231] extension, in addition to the extensions described here.
described here. All examples below assume the relational extension All examples below assume the relational extension is present.
is present.
2. Conventions Used in This Document 2. Conventions Used in This Document
Conventions for notations are as in [I-D.ietf-sieve-3028bis] section Conventions for notations are as in [RFC5228] Section 1.1.
1.1.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
The term "spam" is used in this document to refer to unsolicited or The term "spam" is used in this document to refer to unsolicited or
unwanted email messages. This document does not attempt to define unwanted email messages. This document does not attempt to define
what exactly constitutes spam, or how it should be identified, or what exactly constitutes spam, or how it should be identified, or
what actions should be taken when detected. what actions should be taken when detected.
The term "virus" is used in this document to refer to any type of The term "virus" is used in this document to refer to any type of
message whose content can cause malicious damage. This document does message whose content can cause malicious damage. This document does
not attempt to define what exactly constitutes a virus, or how it not attempt to define what exactly constitutes a virus, or how it
should be identified, or what actions should be taken when detected. should be identified, or what actions should be taken when detected.
3. SIEVE Extensions 3. Sieve Extensions
3.1. General Considerations 3.1. General Considerations
The "spamtest" and "virustest" tests described below evaluate the The "spamtest" and "virustest" tests described below evaluate the
results of implementation-specific spam and virus checks in a results of implementation-specific spam and virus checks in a
portable way. The implementation may, for example, check for third- portable way. The implementation may, for example, check for third-
party spam tool headers and determine how those map into the way the party spam tool headers and determine how those map into the way the
test commands are used. To do this, the underlying SIEVE test commands are used. To do this, the underlying Sieve
implementation provides a normalized result string as one of the implementation provides a normalized result string as one of the
inputs to each test command. The normalized result string is inputs to each test command. The normalized result string is
considered to be the value on the left hand side of the test, and the considered to be the value on the left-hand side of the test, and the
comparison values given in the test command are considered to be on comparison values given in the test command are considered to be on
the right hand side. the right-hand side.
The normalized result starts with a digit string, with its numeric The normalized result starts with a digit string, with its numeric
value within the range of values used by the specific test, value within the range of values used by the specific test,
indicating the severity of spam or viruses in a message or whether indicating the severity of spam or viruses in a message or whether
any tests were done at all. This may optionally be followed by a any tests were done at all. This may optionally be followed by a
space (%x20) character and arbitrary text, or in one specific case a space (%x20) character and arbitrary text, or in one specific case a
single keyword is returned. The numeric value can be compared to single keyword is returned. The numeric value can be compared to
specific values using the SIEVE relational [I-D.ietf-sieve-3431bis] specific values using the Sieve relational [RFC5231] extension in
extension in conjunction with the "i;ascii-numeric" comparator conjunction with the "i;ascii-numeric" comparator [RFC4790], which
[I-D.newman-i18n-comparator], which will test for the presence of a will test for the presence of a numeric value at the start of the
numeric value at the start of the string, ignoring any additional string, ignoring any additional text in the string. The optional
text in the string. The optional text can be used to carry text can be used to carry implementation-specific details about the
implementation specific details about the tests and descriptive tests and descriptive comments about the result. Tests can be done
comments about the result. Tests can be done using standard string using standard string comparators against this text if it helps to
comparators against this text if it helps to refine behavior, however refine behavior; however, this will break portability of the script
this will break portability of the script as the text will likely be as the text will likely be specific to a particular implementation.
specific to a particular implementation.
In addition, the SIEVE relational [I-D.ietf-sieve-3431bis] ":count" In addition, the Sieve relational [RFC5231] ":count" match type can
match type can be used to determine if the underlying implementation be used to determine if the underlying implementation actually did a
actually did a test. If the underlying spam or virus test was done, test. If the underlying spam or virus test was done, the ":count" of
the ":count" of the normalized result will return the numeric value the normalized result will return the numeric value "1", whilst if
"1", whilst if the test was not done, or the SIEVE implementation the test was not done, or the Sieve implementation could not
could not determine if a test was done or not done, the ":count" determine if a test was done or not done, the ":count" value will be
value will be "0" (zero). "0" (zero).
3.2. Test spamtest 3.2. Test spamtest
Usage: spamtest [":percent"] [COMPARATOR] [MATCH-TYPE] Usage: spamtest [":percent"] [COMPARATOR] [MATCH-TYPE]
<value: string> <value: string>
SIEVE implementations that implement the "spamtest" test use an
Sieve implementations that implement the "spamtest" test use an
identifier of either "spamtest" or "spamtestplus" for use with the identifier of either "spamtest" or "spamtestplus" for use with the
capability mechanism. capability mechanism.
If the ":percent" argument is not used with any spamtest test, then If the ":percent" argument is not used with any spamtest test, then
one or both of "spamtest" or "spamtestplus" capability identifiers one or both of "spamtest" or "spamtestplus" capability identifiers
MUST be present. MUST be present.
If the ":percent" argument is used with any spamtest test, then the If the ":percent" argument is used with any spamtest test, then the
"spamtestplus" capability identifier MUST be present. SIEVE "spamtestplus" capability identifier MUST be present. Sieve
implementations MUST return an error if the ":percent" argument is implementations MUST return an error if the ":percent" argument is
used and "spamtestplus" is not specified. used and "spamtestplus" is not specified.
In the interests of brevity and clarity, scripts SHOULD NOT specify In the interests of brevity and clarity, scripts SHOULD NOT specify
both "spamtestplus" and "spamtest" capability identifiers together. both "spamtestplus" and "spamtest" capability identifiers together.
The "spamtest" test evaluates to true if the normalized spamtest The "spamtest" test evaluates to true if the normalized spamtest
result matches the value. The type of match is specified by the result matches the value. The type of match is specified by the
optional match argument, which defaults to ":is" if not specified. optional match argument, which defaults to ":is" if not specified.
3.2.1. spamtest without :percent argument 3.2.1. spamtest without :percent Argument
When the ":percent" argument is not present in the "spamtest" test, When the ":percent" argument is not present in the "spamtest" test,
the normalized result string provided for the left hand side of the the normalized result string provided for the left-hand side of the
test starts with a numeric value in the range "0" (zero) through test starts with a numeric value in the range "0" (zero) through
"10", with meanings summarized below: "10", with meanings summarized below:
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
| spamtest | interpretation | | spamtest | interpretation |
| value | | | value | |
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
| 0 | message was not tested for spam, or SIEVE could not | | 0 | message was not tested for spam, or Sieve could not |
| | determine whether any test was done | | | determine whether any test was done |
| | | | | |
| 1 | message was tested and is clear of spam | | 1 | message was tested and is clear of spam |
| | | | | |
| 2 - 9 | message was tested and may contain spam; a higher | | 2 - 9 | message was tested and may contain spam; a higher |
| | number indicates a greater likelihood of spam | | | number indicates a greater likelihood of spam |
| | | | | |
| 10 | message was tested and definitely contains spam | | 10 | message was tested and definitely contains spam |
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
The underlying SIEVE implementation will map whatever spam check is The underlying Sieve implementation will map whatever spam check is
done into this numeric range, as appropriate. done into this numeric range, as appropriate.
Examples: Examples:
require ["spamtest", "fileinto", require ["spamtest", "fileinto", "relational", "comparator-
"relational", "comparator-i;ascii-numeric"]; i;ascii-numeric"];
if spamtest :value "eq" :comparator "i;ascii-numeric" "0" if spamtest :value "eq" :comparator "i;ascii-numeric" "0"
{ {
fileinto "INBOX.unclassified"; fileinto "INBOX.unclassified";
} }
elsif spamtest :value "ge" :comparator "i;ascii-numeric" "3" elsif spamtest :value "ge" :comparator "i;ascii-numeric" "3"
{ {
fileinto "INBOX.spam-trap"; fileinto "INBOX.spam-trap";
} }
In this example, any message that has not passed through a spam check In this example, any message that has not passed through a spam check
tool will be filed into the mailbox "INBOX.unclassified". Any tool will be filed into the mailbox "INBOX.unclassified". Any
message with a normalized result value greater than or equal to "3" message with a normalized result value greater than or equal to "3"
is filed into a mailbox called "INBOX.spam-trap" in the user's is filed into a mailbox called "INBOX.spam-trap" in the user's
mailstore. mailstore.
3.2.2. spamtest with :percent argument 3.2.2. spamtest with :percent Argument
When the ":percent" argument is present in the "spamtest" test, the When the ":percent" argument is present in the "spamtest" test, the
normalized result string provided for the left hand side of the test normalized result string provided for the left-hand side of the test
starts with a numeric value in the range "0" (zero) through "100", starts with a numeric value in the range "0" (zero) through "100",
with meanings summarized below: with meanings summarized below:
+----------+-------------------------------------------------------+ +----------+-------------------------------------------------------+
| spamtest | interpretation | | spamtest | interpretation |
| value | | | value | |
+----------+-------------------------------------------------------+ +----------+-------------------------------------------------------+
| 0 | message was tested and is clear of spam, or was not | | 0 | message was tested and is clear of spam, or was not |
| | tested for spam, or SIEVE could not determine whether | | | tested for spam, or Sieve could not determine whether |
| | any test was done | | | any test was done |
| | | | | |
| 1 - 99 | message was tested and may contain spam; a higher | | 1 - 99 | message was tested and may contain spam; a higher |
| | percentage indicates a greater likelihood of spam | | | percentage indicates a greater likelihood of spam |
| | | | | |
| 100 | message was tested and definitely contains spam | | 100 | message was tested and definitely contains spam |
+----------+-------------------------------------------------------+ +----------+-------------------------------------------------------+
The underlying SIEVE implementation will map whatever spam check is The underlying Sieve implementation will map whatever spam check is
done into the numeric range, as appropriate. done into the numeric range, as appropriate.
To determine whether the message was tested for spam or not, two To determine whether or not the message was tested for spam, two
options can be used: options can be used:
a. a test with or without the ":percent" argument and ":count" match a. a test with or without the ":percent" argument and ":count" match
type, testing for the value "0" as described in Section 3.1. type, testing for the value "0" as described in Section 3.1.
b. a test without the ":percent" argument using the ":value" match b. a test without the ":percent" argument using the ":value" match
type, testing for the normalized result value "0" as described in type, testing for the normalized result value "0" as described in
Section 3.2.1. Section 3.2.1.
Examples: Examples:
require ["spamtestplus", "fileinto", require ["spamtestplus", "fileinto", "relational",
"relational", "comparator-i;ascii-numeric"]; "comparator-i;ascii-numeric"];
if spamtest :value "eq" if spamtest :value "eq"
:comparator "i;ascii-numeric" "0" :comparator "i;ascii-numeric" "0"
{ {
fileinto "INBOX.unclassified"; fileinto "INBOX.unclassified";
} }
elsif spamtest :percent :value "eq" elsif spamtest :percent :value "eq"
:comparator "i;ascii-numeric" "0" :comparator "i;ascii-numeric" "0"
{ {
fileinto "INBOX.not-spam"; fileinto "INBOX.not-spam";
skipping to change at page 8, line 43 skipping to change at page 6, line 39
In this example, any message that has not passed through a spam check In this example, any message that has not passed through a spam check
tool will be filed into the mailbox "INBOX.unclassified". Any tool will be filed into the mailbox "INBOX.unclassified". Any
message that is classified as definitely not containing spam message that is classified as definitely not containing spam
(normalized result value "0") will be filed into the mailbox (normalized result value "0") will be filed into the mailbox
"INBOX.not-spam". Any message with a normalized result value less "INBOX.not-spam". Any message with a normalized result value less
than "37" is filed into a mailbox called "INBOX.spam-trap" in the than "37" is filed into a mailbox called "INBOX.spam-trap" in the
user's mailstore. Any other normalized result value will result in user's mailstore. Any other normalized result value will result in
the message being discarded. the message being discarded.
Alternatively, the SIEVE relational [I-D.ietf-sieve-3431bis] ":count" Alternatively, the Sieve relational [RFC5231] ":count" match type can
match type can be used: be used:
Examples: Examples:
if spamtest :percent :count "eq" if spamtest :percent :count "eq"
:comparator "i;ascii-numeric" "0" :comparator "i;ascii-numeric" "0"
{ {
fileinto "INBOX.unclassified"; fileinto "INBOX.unclassified";
} }
elsif spamtest :percent :value "eq" elsif spamtest :percent :value "eq"
:comparator "i;ascii-numeric" "0" :comparator "i;ascii-numeric" "0"
skipping to change at page 9, line 33 skipping to change at page 7, line 27
} }
This example will result in exactly the same behavior as the previous This example will result in exactly the same behavior as the previous
one. one.
3.3. Test virustest 3.3. Test virustest
Usage: virustest [COMPARATOR] [MATCH-TYPE] Usage: virustest [COMPARATOR] [MATCH-TYPE]
<value: string> <value: string>
SIEVE implementations that implement the "virustest" test have an Sieve implementations that implement the "virustest" test have an
identifier of "virustest" for use with the capability mechanism. identifier of "virustest" for use with the capability mechanism.
The "virustest" test evaluates to true if the normalized result The "virustest" test evaluates to true if the normalized result
string matches the value. The type of match is specified by the string matches the value. The type of match is specified by the
optional match argument, which defaults to ":is" if not specified. optional match argument, which defaults to ":is" if not specified.
The normalized result string provided for the left side of the test The normalized result string provided for the left side of the test
starts with a numeric value in the range "0" (zero) through "5", with starts with a numeric value in the range "0" (zero) through "5", with
meanings summarized below: meanings summarized below:
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| virustest | interpretation | | virustest | interpretation |
| value | | | value | |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 0 | message was not tested for viruses, or SIEVE could | | 0 | message was not tested for viruses, or Sieve could |
| | not determine whether any test was done | | | not determine whether any test was done |
| | | | | |
| 1 | message was tested and contains no known viruses | | 1 | message was tested and contains no known viruses |
| | | | | |
| 2 | message was tested and contained a known virus which | | 2 | message was tested and contained a known virus that |
| | was replaced with harmless content | | | was replaced with harmless content |
| | | | | |
| 3 | message was tested and contained a known virus which | | 3 | message was tested and contained a known virus that |
| | was "cured" such that it is now harmless | | | was "cured" such that it is now harmless |
| | | | | |
| 4 | message was tested and possibly contains a known | | 4 | message was tested and possibly contains a known |
| | virus | | | virus |
| | | | | |
| 5 | message was tested and definitely contains a known | | 5 | message was tested and definitely contains a known |
| | virus | | | virus |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
The underlying SIEVE implementation will map whatever virus checks The underlying Sieve implementation will map whatever virus checks
are done into this numeric range, as appropriate. If the message has are done into this numeric range, as appropriate. If the message has
not been categorized by any virus checking tools, then the virustest not been categorized by any virus checking tools, then the virustest
result is "0". result is "0".
Example: Example:
require ["virustest", "fileinto", require ["virustest", "fileinto", "relational", "comparator-
"relational", "comparator-i;ascii-numeric"]; i;ascii-numeric"];
if virustest :value "eq" :comparator "i;ascii-numeric" "0" if virustest :value "eq" :comparator "i;ascii-numeric" "0"
{ {
fileinto "INBOX.unclassified"; fileinto "INBOX.unclassified";
} }
if virustest :value "eq" :comparator "i;ascii-numeric" "4" if virustest :value "eq" :comparator "i;ascii-numeric" "4"
{ {
fileinto "INBOX.quarantine"; fileinto "INBOX.quarantine";
} }
elsif virustest :value "eq" :comparator "i;ascii-numeric" "5" elsif virustest :value "eq" :comparator "i;ascii-numeric" "5"
skipping to change at page 11, line 10 skipping to change at page 9, line 10
In this example, any message that has not passed through a virus In this example, any message that has not passed through a virus
check tool will be filed into the mailbox "INBOX.unclassified". Any check tool will be filed into the mailbox "INBOX.unclassified". Any
message with a normalized result value equal to "4" is filed into a message with a normalized result value equal to "4" is filed into a
mailbox called "INBOX.quarantine" in the user's mailstore. Any mailbox called "INBOX.quarantine" in the user's mailstore. Any
message with a normalized result value equal to "5" is discarded message with a normalized result value equal to "5" is discarded
(removed) and not delivered to the user's mailstore. (removed) and not delivered to the user's mailstore.
4. Security Considerations 4. Security Considerations
SIEVE implementations SHOULD ensure that "spamtest" and "virustest" Sieve implementations SHOULD ensure that "spamtest" and "virustest"
tests only report spam and virus test results for messages that tests only report spam and virus test results for messages that
actually have gone through a legitimate spam or virus check process. actually have gone through a legitimate spam or virus check process.
In particular, if such checks rely on the addition and subsequent In particular, if such checks rely on the addition and subsequent
checking of private header fields, it is the responsibility of the checking of private header fields, it is the responsibility of the
implementation to ensure that such headers cannot be spoofed by the implementation to ensure that such headers cannot be spoofed by the
sender or intermediary and thereby prevent the implementation from sender or intermediary and thereby prevent the implementation from
being tricked into returning the wrong result for the test. being tricked into returning the wrong result for the test.
Server administrators must ensure that the virus checking tools are Server administrators must ensure that the virus checking tools are
kept up to date, to provide reasonable protection for users using the kept up to date, to provide reasonable protection for users using the
"virustest" test. Users should be made aware of the fact that the "virustest" test. Users should be made aware of the fact that the
"virustest" test does not provide a 100% reliable way to remove all "virustest" test does not provide a 100% reliable way to remove all
viruses, and they should continue to exercise caution when dealing viruses, and they should continue to exercise caution when dealing
with messages of unknown content and origin. with messages of unknown content and origin.
Beyond that, the "spamtest" and "virustest" extensions do not raise Beyond that, the "spamtest" and "virustest" extensions do not raise
any security considerations that are not present in the base any security considerations that are not present in the base
[I-D.ietf-sieve-3028bis] protocol, and these issues are discussed in [RFC5228] protocol, and these issues are discussed in [RFC5228].
[I-D.ietf-sieve-3028bis].
5. IANA Considerations 5. IANA Considerations
The following templates specify the IANA registration of the Sieve The following templates specify the IANA registration of the Sieve
extensions specified in this document. The registrations for extensions specified in this document. The registrations for
"spamtest" and "virustest" replace those from in [RFC3685]: "spamtest" and "virustest" replace those from [RFC3685]:
5.1. spamtest registration 5.1. spamtest Registration
To: iana@iana.org To: iana@iana.org
Subject: Registration of new Sieve extension Subject: Registration of new Sieve extension
Capability name: spamtest Capability name: spamtest
Capability keyword: spamtest Description: Provides a test to check for varying likelihood of
Capability arguments: N/A an email message being spam.
Standards Track/IESG-approved experimental RFC number: this RFC RFC number: RFC 5235
Person and email address to contact for further information: Contact address: The Sieve discussion list <ietf-mta-filters@imc.org>
Cyrus Daboo
<mailto:cyrus@daboo.name>
This information should be added to the list of sieve extensions This information has been added to the list of Sieve extensions given
given on http://www.iana.org/assignments/sieve-extensions. on http://www.iana.org/assignments/sieve-extensions.
5.2. virustest registration 5.2. virustest Registration
To: iana@iana.org To: iana@iana.org
Subject: Registration of new Sieve extension Subject: Registration of new Sieve extension
Capability name: virustest Capability name: virustest
Capability keyword: virustest Description: Provides a test to check for varying likelihood of
Capability arguments: N/A there being malicious content in an email message.
Standards Track/IESG-approved experimental RFC number: this RFC RFC number: RFC 5235
Person and email address to contact for further information: Contact address: The Sieve discussion list <ietf-mta-filters@imc.org>
Cyrus Daboo
<mailto:cyrus@daboo.name>
This information should be added to the list of sieve extensions This information has been added to the list of Sieve extensions given
given on http://www.iana.org/assignments/sieve-extensions. on http://www.iana.org/assignments/sieve-extensions.
5.3. spamtestplus registration 5.3. spamtestplus Registration
To: iana@iana.org To: iana@iana.org
Subject: Registration of new Sieve extension Subject: Registration of new Sieve extension
Capability name: spamtestplus Capability name: spamtestplus
Capability keyword: spamtestplus Description: Provides a test to check for varying likelihood of
Capability arguments: :percent an email message being spam, possibly using a
Standards Track/IESG-approved experimental RFC number: this RFC percentage range.
Person and email address to contact for further information: RFC number: RFC 5235
Contact address: The Sieve discussion list <ietf-mta-filters@imc.org>
Cyrus Daboo
<mailto:cyrus@daboo.name>
This information should be added to the list of sieve extensions This information has been added to the list of Sieve extensions given
given on http://www.iana.org/assignments/sieve-extensions. on http://www.iana.org/assignments/sieve-extensions.
6. References 6. References
6.1. Normative References 6.1. Normative References
[I-D.ietf-sieve-3028bis]
Showalter, T. and P. Guenther, "Sieve: An Email Filtering
Language", draft-ietf-sieve-3028bis-07 (work in progress),
June 2006.
[I-D.ietf-sieve-3431bis]
Segmuller, W. and B. Leiba, "Sieve Extension: Relational
Tests", draft-ietf-sieve-3431bis-04 (work in progress),
December 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2. Informative References [RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet
Application Protocol Collation Registry", RFC 4790, March
2007.
[I-D.newman-i18n-comparator] [RFC5228] Guenther, P., Ed., and T. Showalter, Ed., "Sieve: An Email
Newman, C., "Internet Application Protocol Collation Filtering Language", RFC 5228, January 2008.
Registry", draft-newman-i18n-comparator-12 (work in
progress), June 2006. [RFC5231] Segmuller, W. and B. Leiba, "Sieve Email Filtering:
Relational Extension", RFC 5231, January 2008.
6.2. Informative References
[RFC3685] Daboo, C., "SIEVE Email Filtering: Spamtest and VirusTest [RFC3685] Daboo, C., "SIEVE Email Filtering: Spamtest and VirusTest
Extensions", RFC 3685, February 2004. Extensions", RFC 3685, February 2004.
Appendix A. Acknowledgments Appendix A. Acknowledgments
Thanks to Mark E. Mallett, Tony Hansen, Jutta Degener, Ned Freed, Thanks to Mark E. Mallett, Tony Hansen, Jutta Degener, Ned Freed,
Ashish Gawarikar, Alexey Melnikov, Nigel Swinson and Aaron Stone for Ashish Gawarikar, Alexey Melnikov, Nigel Swinson, and Aaron Stone for
comments and corrections. comments and corrections.
Appendix B. Important Changes since RFC 3685
Listed below are some of the major changes from the previous
specification [RFC3685], which this one supersedes.
1. A ":percent" argument has been added to the "spamtest" test adding
a new 0-100 numerical range for test results.
2. A "spamtestplus" requires item has been added to indicate the
presence of this extension in scripts.
3. The "count" match type from [RFC5231] can now be used to determine
whether or not a message was tested.
4. Clarified that "test not done" also means "Sieve system could not
determine if a test was done".
Author's Address Author's Address
Cyrus Daboo Cyrus Daboo
Email: cyrus@daboo.name EMail: cyrus@daboo.name
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skipping to change at page 16, line 28 skipping to change at line 527
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
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