Network Working Group Tim Martin Document: draft-martin-managesieve-05.txt Mirapoint Inc. Expires February 22, 2006 Alexey Melnikov Isode Limited 22 August 2005 A Protocol for Remotely Managing Sieve Scripts <draft-martin-managesieve-05.txt> Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Abstract Sieve scripts allow users to filter incoming email. Message stores are commonly sealed servers so users cannot log into them, yet users must be able to update their scripts on them. This document describes a protocol "sieve" for securely managing Sieve scripts on a remote server. This protocol allows a user to have multiple scripts, and also alerts a user to syntactically flawed scripts. This an interim measure as it is hoped that eventually Sieve scripts will be stored on ACAP. This document is intended to proceed on the experimental track. Table of Contents Status of this Memo . . . . . . . . . . . . . . . . . . . . . . . . 1 Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Conventions Used in the Document . . . . . . . . . . . . . . 4 1.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4. Response Codes . . . . . . . . . . . . . . . . . . . . . . . 5 1.5. Active Script . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6. Quotas . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.7. Script Names . . . . . . . . . . . . . . . . . . . . . . . . 7 1.8. Capabilities . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Commands . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1. AUTHENTICATE Command . . . . . . . . . . . . . . . . . . . . 8 2.2. STARTTLS Command . . . . . . . . . . . . . . . . . . . . . . 10 2.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . . . . . 10 2.4. CAPABILITY Command . . . . . . . . . . . . . . . . . . . . . 11 2.5. HAVESPACE Command . . . . . . . . . . . . . . . . . . . . . . 11 2.6. PUTSCRIPT Command . . . . . . . . . . . . . . . . . . . . . . 11 2.7. LISTSCRIPTS Command . . . . . . . . . . . . . . . . . . . . . 13 2.8. SETACTIVE Command . . . . . . . . . . . . . . . . . . . . . . 13 2.9. GETSCRIPT Command . . . . . . . . . . . . . . . . . . . . . . 13 2.10. DELETESCRIPT Command . . . . . . . . . . . . . . . . . . . . 14 3. Sieve URL Scheme . . . . . . . . . . . . . . . . . . . . . . 14 4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 15 5. Security Considerations . . . . . . . . . . . . . . . . . . . 18 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7.1. Normative References . . . . . . . . . . . . . . . . . . . . 7.2. Informative References . . . . . . . . . . . . . . . . . . . 8. Author's Address . . . . . . . . . . . . . . . . . . . . . . 1. Introduction 1.1. Changes [[Note to RFC editor: please delete this section before publication]] Changes since 04 -Updated boilerplate and some references. Added Alexey as co-editor. -Minor ABNF fixes -Cleaned up terminology (for example, made more consistent with SASL) -Added more examples, fixed some existing examples -Clarified that STARTTLS command is optional -Clarified that disabling an active script when there is no script active is not an error. Changes since 03 -Add referals and Sieve URLs -Lots of spelling/grammer fixes -Don't give capabilities after successful STARTTLS. This is because it isn't consistant with AUTHENTICATE. There is language specifying that a client should re-issue a CAPABILITY command after AUTHENTICATE/STARTTLS. -Putting a script of length 0 doesn't remove the script. If this functionality is desired, the DELETESCRIPT command should be used. Changes since 02 -add BYE response -typo on line 588 -allow ANONYMOUS access for sieve script verification -updated SIEVE spec reference Changes since 01 -changed contact info Changes since 00 -added response codes (from ACAP) -removed special-ok response from authenticate command (response codes obsolete it) -changed service name to "sieve" -ABNF fixes -Alexey's wording changes -Eliminated lame PLAIN paragraph Changes since PRE -dropped synchronized literals. added HAVESPACE command -changed capability response syntax. added CAPABILITY command -allowed pipelining - "sieve" -> "Sieve". Other minor fixes -made script names more flexible -added starttls support 1.2. Conventions Used in the Document 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]. In examples, "C:" and "S:" indicate lines sent by the client and server respectively. Line breaks that do not start a new "C:" or "S:" exist for editorial reasons. 1.3. Syntax This a line oriented protocol much like [IMAP4rev1] or [ACAP]. There are three types: ATOMS, numbers and strings. Strings may be quoted or literal. See [ACAP] for detailed descriptions of these types. Each command consists of an atom followed by zero or more strings and numbers terminated by a newline. All client queries are replied to with either an OK, NO, or BYE response. Each response may be followed by a response code (see response codes section) and by a string consisting of human readable text in the local language. The contents of the string SHOULD be shown to the user and implementations MUST NOT attempt to parse the message for meaning. The BYE response may be used if the server wishes to close the connection. A server may wish to do this because the client was idle for too long or there were too many failed authentication attempts. This response can be issued at any time and should be immediately followed by a server hang-up of the connection. If a server has a inactivity timeout resulting in client autologout it MUST be no less than 30 minutes. <<IANA registration is pending. Current implementations generally use port number 2000.>> 1.4. Response Codes An OK, NO, or BYE response from the server MAY contain a response code to describe the event in a more detailed machine parsable fashion. A response code consists of data inside parentheses in the form of an atom, possibly followed by a space and arguments. Response codes are defined when there is a specific action that a client can take based upon the additional information. In order to support future extension, the response code is represented as a slash-separated hierarchy with each level of hierarchy representing increasing detail about the error. Clients MUST tolerate additional hierarchical response code detail which they don't understand. The currently defined response codes are: AUTH-TOO-WEAK This response code is returned on a tagged NO result from an AUTHENTICATE command. It indicates that site security policy forbids the use of the requested mechanism for the specified authentication identity. ENCRYPT-NEEDED This response code is returned on NO result from an AUTHENTICATE command. It indicates that site security policy requires the use of a strong encryption mechanism for the specified authentication identity and mechanism. QUOTA The command would have placed the user above the site-defined quota constraints. REFERRAL This response code may be returned with a BYE result from any command, and includes a mandatory parameter that indicates what server to access to manage this user's sieve scripts. The server will be specified by a Sieve URL (see "Sieve URL Scheme" section). The scriptname portion of the URL MUST NOT be specified. The client should authenticate to the specified server and use it for all further commands in the current session. SASL This response code can occur in the OK response to a successful AUTHENTICATE command and includes the optional final server response data from the server as specified by [SASL]. TRANSITION-NEEDED This response code occurs on a NO response to an AUTHENTICATE command. It indicates that the user name is valid, but the entry in the authentication database needs to be updated in order to permit authentication with the specified mechanism. This can happen if a user has an entry in a system authentication database such as Unix /etc/passwd, but does not have credentials suitable for use by the specified mechanism. TRYLATER A command failed due to a temporary server failure. The client MAY continue using local information and try the command later. Client implementations MUST tolerate response codes that they do not recognize. 1.5. Active Script A user may have multiple Sieve scripts on the server, yet only one script may be used for filtering of incoming messages. This is the active script. Users may have zero or one active scripts and MUST use the SETACTIVE command described below for changing the active script or disabling Sieve processing. For example, a user may have an everyday script they normally use and a special script they use when they go on vacation. Users can change which script is being used without having to download and upload a script stored somewhere else. 1.6. Quotas Servers SHOULD impose quotas to prevent malicious users from overflowing available storage. If a command would place a user over a quota setting, servers MUST reply with a NO response. Client implementations MUST be able to handle commands failing because of quota restrictions. 1.7. Script Names Sieve script names may contain any valid UTF8 characters, but names must be at least one octet long. Zero octets script name has special meaning. (see SETACTIVE command section) Servers MUST allow names of up to 128 UTF8 octets in length, and may allow longer names. 1.8. Capabilities Server capabilities are sent by the server upon a client connection. Clients may request the capabilities at a later time by issuing the CAPABILITY command described later. The capabilities consist of a series of lines each with one or two strings. The first string is the name of the capability. The second optional string is the value associated with that capability. The following capabilities are defined here: IMPLEMENTATION - Name of implementation and version SASL - List of SASL mechanisms supported by the server, each separated by a space SIEVE - List of space separated Sieve extensions supported STARTTLS - If TLS[TLS] is supported by this implementation A client implementation MUST ignore any other capabilities given that it does not understand. Example: S: "IMPLEMENTATION" "CMU Cyrus Sieved v001" S: "SASL" "KERBEROS_V4 GSSAPI" S: "SIEVE" "FILEINTO VACATION" S: "STARTTLS" S: OK 2. Commands The following commands are valid. Prior to successful authentication only the AUTHENTICATE, CAPABILITY, STARTTLS, and LOGOUT commands are valid. Servers MUST reject all other commands with a NO response. Clients may pipeline commands (send more than one command at a time without waiting for completion of the first command ). However, a group of commands sent together MUST NOT have an AUTHENTICATE, a STARTTLS or a HAVESPACE command anywhere but the last command in the list. 2.1. AUTHENTICATE Command Arguments: String - mechanism String - initial data (optional) The AUTHENTICATE command indicates a SASL [SASL] authentication mechanism to the server. If the server supports the requested authentication mechanism, it performs an authentication protocol exchange to authenticate and identify the user. Optionally, it also negotiates a security layer for subsequent protocol interactions. If the requested authentication mechanism is not supported, the server rejects the AUTHENTICATE command by sending a NO response. The authentication protocol exchange consists of a series of server challenges and client responses that are specific to the selected authentication mechanism. A server challenge consists of a string followed by an endline. The contents of the string is a base-64 encoding of the SASL data. A client response consists of a string with the base-64 encoding of the SASL data followed by an endline. If the mechanism dictates that the final response be sent by the server this data MAY be placed within the data portion of the SASL response code to save a round trip. The optional initial-response argument to the AUTHENTICATE command is used to save a round trip when using authentication mechanisms that are defined to send no data in the initial challenge. When the initial-response argument is used with such a mechanism, the initial empty challenge is not sent to the client and the server uses the data in the initial-response argument as if it were sent in response to the empty challenge. If the initial-response argument to the AUTHENTICATE command is used with a mechanism that sends data in the initial challenge, the server rejects the AUTHENTICATE command by sending a tagged NO response. The service name specified by this protocol's profile of SASL is "sieve". If a security layer is negotiated through the SASL authentication exchange, it takes effect immediately following the CRLF that concludes the authentication exchange for the client, and the CRLF of the OK response for the server. Implementations MAY advertise the ANONYMOUS SASL mechanism [SASL-ANON]. This indicates that the server supports ANONYMOUS sieve script syntax verification. Only the CAPABILITY, PUTSCRIPT and LOGOUT commands are available to the anonymous user. All other commands MUST give NO responses. Furthermore the PUTSCRIPT command SHOULD NOT store any data. In this mode a positive response to the PUTSCRIPT command indicates that the given script does not have any syntax errors. Server implementations SHOULD support SASL proxy authentication so that an administrator can administer a user's scripts. Proxy authentication is when a user authenticates as himself but requests the server to act (authorize) as another user. If an AUTHENTICATE command fails with a NO response, the client may try another authentication mechanism by issuing another AUTHENTICATE command. In other words, the client may request authentication types in decreasing order of preference. <<Make sure this conforms to 2222bis>> Examples: S: "IMPLEMENTATION" "CMU Cyrus Sieved v001" S: "SASL" "KERBEROS_V4 GSSAPI" S: "SIEVE" "FILEINTO VACATION" S: "STARTTLS" S: OK C: Authenticate "KERBEROS_V4" S: "6UM4Ig==" C: "BAYBQU5EUkVXLkNNVS5FRFUAOCjDCH77GOzSSOF1Df2Kb0zzPe QJIrweAPyo6Q1T9xuYtCGylDqRYlbUFa77esDOtBJdDE5qRXcwHXQE5Dg amqj0LqecZtKUCc8g2xpcqxn1fc/CH6QdZLOAGVpHTN1AX2Y=" S: "cmnEYo1x6wc=" C: "kjuaMkUeg2okQh+we2uiJw==" S: OK C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xu" S: BYE "Too many failed authentication attempts" Server closes connection <<Add an example with SASL response code and usage of literals. Replace Kerberos V4 example with something more recent.>> 2.2. STARTTLS Command Support for STARTTLS command in servers is optional. Its availability is advertised with "STARTTLS" capability as described in section <<1.8>>. The STARTTLS command requests to commencement of a TLS negotiation. The negotiation begins immediately after the CRLF in the OK response. After a client issues a STARTTLS command, it MUST NOT issue further commands until a server response is seen and the TLS negotiation is complete. The STARTTLS command is only valid in non-authenticated state. The server remains in non-authenticated state, even if client credentials are supplied during the TLS negotiation. The SASL [SASL] EXTERNAL mechanism MAY be used to authenticate once TLS client credentials are successfully exchanged, but servers supporting the STARTTLS command are not required to support the EXTERNAL mechanism. After the TLS layer is established, the server MUST re-issue the capability results, followed by an OK response. This is necessary to protect against man-in-the-middle attacks which alter the capabilities list prior to STARTTLS. The client MUST discard cached capability information and replace it with the new information. The server MAY advertise different capabilities after STARTTLS. Example: C: STARTTLS S: OK <TLS negotiation, further commands are under TLS layer> S: "IMPLEMENTATION" "CMU Cyrus Sieved v001" S: "SASL" "PLAIN KERBEROS_V4 GSSAPI" S: "SIEVE" "FILEINTO VACATION" S: OK 2.3. LOGOUT Command The client sends the LOGOUT command when it is finished with a connection and wishes to terminate it. The server MUST reply with an OK response and terminate the connection. The server MUST ignore commands issued by the client after the LOGOUT command. Example: C: Logout S: OK <connection terminated> 2.4. CAPABILITY Command The CAPABILITY command requests the server capabilities as described earlier in this document. While the capabilities are sent upon connection, they may change during authentication. The client SHOULD issue a CAPABILITY command after successful authentication or after negotiating a security layer using STARTTLS. Example: S: "IMPLEMENTATION" "CMU Cyrus Sieved v001" S: "SASL" "PLAIN KERBEROS_V4 GSSAPI" S: "SIEVE" "FILEINTO VACATION" S: "STARTTLS" S: OK 2.5. HAVESPACE Command Arguments: String - name Number - size The HAVESPACE command is used to query the server for available space. Clients specify the name they wish to save the script as and it's size in octets. Servers respond with an NO if storing a script with that name and size would fail or OK otherwise. Clients should issue this command before attempting to place a script on the server. Example: C: HAVESPACE "myscript" 999999 S: NO (QUOTA) "Quota exceeded" C: HAVESPACE "foobar" 435 S: OK 2.6. PUTSCRIPT Command Arguments: String - Script name String - Script content The PUTSCRIPT command is used by the client to submit a Sieve script to the server. If the script already exists upon success the old script will be overwritten. The old script MUST NOT be overwritten if PUTSCRIPT fails in any way. A script of zero length SHOULD be disallowed. This command places the script on the server. It does not affect whether the script is processed on incoming mail. The SETACTIVE command is used to mark a script as active. When submitting large scripts clients SHOULD use the HAVESPACE command beforehand to query if the server is willing to accept a script of that size. The server MUST check the submitted script for syntactic validity. If the script fails this test the server MUST reply with a NO response. Any script that fails the validity test MUST NOT be stored on the server. The message given with a NO response MUST be human readable and SHOULD contain a specific error message giving line number of the first error. Implementors should strive to produce helpful error messages similar to those given by programming language compilers. Client implementations should note that this may be a multiline literal string with more than one error message separated by newlines. Example: C: Putscript "foo" {31+} C: #comment C: InvalidSieveCommand C: S: NO "line 2: Syntax error" C: Putscript "mysievescript" {110+} C: require ["fileinto"]; C: C: if envelope :contains "to" "tmartin+sent" { C: fileinto "INBOX.sent"; C: } S: OK 2.7. LISTSCRIPTS Command This command lists the scripts the user has on the server. Upon success a list of linebreak separated script names is returned followed by an OK response. If there exists an active script the atom ACTIVE is appended to the line of that script. The ACTIVE string MUST NOT appear on more than one response line. Example: C: Listscripts S: "summer_script" S: "vacation_script" S: "main_script" ACTIVE S: OK 2.8. SETACTIVE Command Arguments: String - script name This command sets a script active. If the script name is the empty string (i.e. "") then any active script is disabled. Disabling an active script when there is no script active is not an error and MUST result in OK reply. If the script does not exist on the server then the server MUST reply with a NO response. Examples: C: Setactive "vacationscript" S: Ok C: Setactive "" S: Ok C: Setactive "baz" S: No "There is no script by that name" 2.9. GETSCRIPT Command Arguments: String - Script name This command gets the contents of the specified script. If the script does not exist the server MUST reply with a NO response. Upon success a string with the contents of the script is returned followed by a OK response. Example: C: Getscript "myscript" S: {48+} S: #this is my wonderful script S: reject "I reject all"; S: S: OK 2.10. DELETESCRIPT Command Parameters: sieve-name - Script name This command is used to delete a user's Sieve script. Servers MUST reply with a NO response if the script does not exist. The server MUST NOT allow the client to delete an active script and reply with a NO response if attempted. If a client wishes to delete an active script it should use the SETACTIVE command to disable the script first. Example: C: Deletescript "foo" S: Ok C: Deletescript "baz" S: No "You may not delete an active script" 3. Sieve URL Scheme URL scheme name: "sieve" URL scheme syntax: Described using ABNF [ABNF] and ABNF entities from RFC 2396 <<Update reference>>. sieveurl = "sieve://" [ hostport ] "/" scriptname scriptname = *pchar Character encoding considerations: The script name, if present, is in UTF-8. Non-ASCII characters must be escaped as described in RFC 2396 <<Update>>. Intended usage: A sieve URL identifies a sieve server or a sieve script on a sieve server. <<The latter always have the application/sieve MIME type.>> Applications and/or protocols which use this URL scheme name: The protocol is described in this document. Interoperability considerations: None. Security considerations: None. Relevant publications: This document and <<RFC 3028>>. Person & email address to contact for further information: Alexey Melnikov <alexey.melnikov@isode.com> Author/Change controller: Alexey Melnikov. 4. Formal Syntax The following syntax specification uses the augmented Backus-Naur Form (BNF) notation as specified in [ABNF]. This uses the ABNF core rules as specified in Appendix A of the ABNF specification [ABNF]. Except as noted otherwise, all alphabetic characters are case- insensitive. The use of upper or lower case characters to define token strings is for editorial clarity only. Implementations MUST accept these strings in a case-insensitive fashion. SAFE-CHAR = %x01-09 / %x0B-0C / %x0E-21 / %x23-5B / %x5D-7F ;; any TEXT-CHAR except QUOTED-SPECIALS QUOTED-CHAR = SAFE-UTF8-CHAR / "\" QUOTED-SPECIALS QUOTED-SPECIALS = <"> / "\" SAFE-UTF8-CHAR = SAFE-CHAR / UTF8-2 / UTF8-3 / UTF8-4 / UTF8-5 / UTF8-6 UTF8-1 = %x80-BF UTF8-2 = %xC0-DF UTF8-1 UTF8-3 = %xE0-EF 2UTF8-1 UTF8-4 = %xF0-F7 3UTF8-1 UTF8-5 = %xF8-FB 4UTF8-1 UTF8-6 = %xFC-FD 5UTF8-1 auth-type = <"> auth-type-name <"> auth-type-name = iana-token ;; as defined in SASL [SASL] command = command-authenticate / command-logout / command-getscript / command-setactive / command-listscripts / command-deletescript / command-putscript / command-capability / command-havespace / command-starttls command-authenticate = "AUTHENTICATE" SP auth-type [SP string] *(CRLF string) command-capability = "CAPABILITY" CRLF command-deletescript = "DELETESCRIPT" SP sieve-name CRLF command-getscript = "GETSCRIPT" SP sieve-name CRLF command-havespace = "HAVESPACE" SP sieve-name SP number CRLF command-listscripts = "LISTSCRIPTS" CRLF command-logout = "LOGOUT" CRLF command-putscript = "PUTSCRIPT" SP sieve-name SP string CRLF command-setactive = "SETACTIVE" SP sieve-name CRLF command-starttls = "STARTTLS" CRLF literal = "{" number "+}" CRLF *OCTET ;; The number represents the number of octets. ;; Sieve scripts MUST be sent as literal-utf8. ;; <<literal-utf8>> is defined in ACAP. number = 1*DIGIT ;; A 32-bit unsigned number. ;; (0 <= n < 4,294,967,296) quoted = <"> *1024QUOTED-CHAR <"> ;; limited to 1024 octets between the <">s resp-code = "AUTH-TOO-WEAK" / "ENCRYPT-NEEDED" / "QUOTA" / resp-code-sasl / resp-code-referral "TRANSITION-NEEDED" / "TRYLATER" / resp-code-ext resp-code-referral = "REFERRAL" SP sieveurl resp-code-sasl = "SASL" SP string resp-code-ext = iana-token [SP extension-data] ;; unknown codes MUST be tolerated by the client response = response-authenticate / response-logout / response-getscript / response-setactive / response-listscripts / response-deletescript / response-putscript / response-capability / response-havespace / response-starttls response-authenticate = *(string CRLF) (response-oknobye) response-capability = *(string [SP string] CRLF) response-oknobye response-deletescript = response-oknobye response-getscript = [string CRLF] response-oknobye response-havespace = response-oknobye response-listscripts = *(sieve-name [SP "ACTIVE"] CRLF) response-oknobye ;; ACTIVE may only occur with one sieve-name response-logout = response-oknobye response-oknobye = ("OK" / "NO" / "BYE") [SP "(" resp-code ")"] [SP string] CRLF response-putscript = response-oknobye response-setactive = response-oknobye response-starttls = response-oknobye sieve-name = string string = quoted / literal 5. Security Considerations The AUTHENTICATE command uses SASL [SASL] and possibly TLS [TLS] to provide basic authentication, authorization, integrity and privacy services. When a SASL mechanism is used the security considerations for that mechanism apply. This protocol transactions are susceptible to passive observers or man in the middle attacks which alter the data, unless the optional encryption and integrity services of the AUTHENTICATE command are enabled, or an external security mechanism is used for protection. It may be useful to allow configuration of both clients and servers to refuse to transfer sensitive information in the absence of strong encryption. 6. IANA Considerations IANA is requested to reserve TCP port number 2000 for use with the Manage Sieve protocol described in this document. <<Anything else, e.g. capability's registry?>> 7. References 7.1. Normative References [KEYWORDS] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997 <ftp://ftp.isi.edu/in-notes/rfc2119.txt> [ABNF] Crocker, Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium, Demon Internet Ltd, November 1997. <<Needs updating>> [ACAP] Newman, Myers, "ACAP -- Application Configuration Access Proto- col", RFC 2244, Innosoft, Netscape, November 1997. [SASL] Myers, J., "Simple Authentication and Security Layer (SASL)", RFC 2222, Netscape Communications, October 1997. <<Needs updating>> [SASL-ANON] Newman, C., "Anonymous SASL Mechanism", RFC 2245, November 1997. <<Needs updating>> [SIEVE] Guenther, P. and Showalter, T., "Sieve: An Email Filtering Language", Work in Progress, draft-ietf-sieve-3028bis-XX.txt [TLS] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. <<Needs updating>> [RFC 2396] <<Update reference>>. 7.2. Informative References [IMAP4rev1] Crispin, M., "Internet Message Access Protocol - Version 4rev1", RFC 3501, March 2003. [PLAIN] Newman, C. "Using TLS with IMAP, POP3 and ACAP", RFC 2595, Innosoft, June 1999. <<Needs updating>> <<Need to update references>> 8. Author's Address Tim Martin Mirapoint Inc. 909 Hermosa Court Sunnyvale, CA 94085 Phone: (408) 720-3835 EMail: timmartin@alumni.cmu.edu Alexey Melnikov Isode Ltd. 5 Castle Business Village 36 Station Road Hampton, Middlesex, TW12 2BX, GB Email: alexey.melnikov@isode.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. The IETF has been notified of intellectual property rights claimed in regard to some or all of the specification contained in this document. For more information consult the online list of claimed rights. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 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 (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Appendix A. Acknowledgments Thanks to Simon Josefsson, Larry Greenfield, Allen Johnson, Chris Newman, Lyndon Nerenberg, Tim Showalter, Sarah Robeson, and Walter Wong for help with this document.