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diff --git a/imap/docs/rfc/rfc5464.txt b/imap/docs/rfc/rfc5464.txt new file mode 100644 index 00000000..645bfd9a --- /dev/null +++ b/imap/docs/rfc/rfc5464.txt @@ -0,0 +1,1177 @@ + + + +Network Working Group C. Daboo +Request for Comments: 5464 Apple, Inc. +Category: Standards Track February 2009 + + + The IMAP METADATA Extension + +Status of This Memo + + 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 + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Abstract + + The METADATA extension to the Internet Message Access Protocol + permits clients and servers to maintain "annotations" or "metadata" + on IMAP servers. It is possible to have annotations on a per-mailbox + basis or on the server as a whole. For example, this would allow + comments about the purpose of a particular mailbox to be "attached" + to that mailbox, or a "message of the day" containing server status + information to be made available to anyone logging in to the server. + + + + + + + + + + + + + + + + + + + + + + + + + + + +Daboo Standards Track [Page 1] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +Table of Contents + + 1. Introduction and Overview . . . . . . . . . . . . . . . . . . 3 + 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 + 3. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3.2. Namespace of Entries . . . . . . . . . . . . . . . . . . . 4 + 3.2.1. Entry Names . . . . . . . . . . . . . . . . . . . . . 5 + 3.3. Private versus Shared and Access Control . . . . . . . . . 6 + 4. IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . . 7 + 4.1. General Considerations . . . . . . . . . . . . . . . . . . 7 + 4.2. GETMETADATA Command . . . . . . . . . . . . . . . . . . . 8 + 4.2.1. MAXSIZE GETMETADATA Command Option . . . . . . . . . . 9 + 4.2.2. DEPTH GETMETADATA Command Option . . . . . . . . . . . 10 + 4.3. SETMETADATA Command . . . . . . . . . . . . . . . . . . . 10 + 4.4. METADATA Response . . . . . . . . . . . . . . . . . . . . 12 + 4.4.1. METADATA Response with Values . . . . . . . . . . . . 13 + 4.4.2. Unsolicited METADATA Response without Values . . . . . 13 + 5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 14 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 + 6.1. Entry and Attribute Registration Template . . . . . . . . 16 + 6.2. Server Entry Registrations . . . . . . . . . . . . . . . . 16 + 6.2.1. /shared/comment . . . . . . . . . . . . . . . . . . . 17 + 6.2.2. /shared/admin . . . . . . . . . . . . . . . . . . . . 17 + 6.3. Mailbox Entry Registrations . . . . . . . . . . . . . . . 17 + 6.3.1. /shared/comment . . . . . . . . . . . . . . . . . . . 18 + 6.3.2. /private/comment . . . . . . . . . . . . . . . . . . . 18 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 18 + 8. Normative References . . . . . . . . . . . . . . . . . . . . . 19 + Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 19 + + + + + + + + + + + + + + + + + + + + + +Daboo Standards Track [Page 2] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +1. Introduction and Overview + + The goal of the METADATA extension is to provide a means for clients + to set and retrieve "annotations" or "metadata" on an IMAP server. + The annotations can be associated with specific mailboxes or the + server as a whole. The server can choose to support only server + annotations or both server and mailbox annotations. + + A server that supports both server and mailbox annotations indicates + the presence of this extension by returning "METADATA" as one of the + supported capabilities in the CAPABILITY command response. + + A server that supports only server annotations indicates the presence + of this extension by returning "METADATA-SERVER" as one of the + supported capabilities in the CAPABILITY command response. + + A server that supports unsolicited annotation change responses MUST + support the "ENABLE" [RFC5161] extension to allow clients to turn + that feature on. + + The METADATA extension adds two new commands and one new untagged + response to the IMAP base protocol. + + This extension makes the following changes to the IMAP protocol: + + o adds a new SETMETADATA command + + o adds a new GETMETADATA command + + o adds a new METADATA untagged response + + o adds a new METADATA response code + + The rest of this document describes the data model and protocol + changes more rigorously. + +2. Conventions Used in This 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 [RFC2119]. + + Whitespace and line breaks have been added to the examples in this + document to promote readability. + + + + +Daboo Standards Track [Page 3] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +3. Data Model + +3.1. Overview + + Mailboxes or the server as a whole may have zero or more annotations + associated with them. An annotation contains a uniquely named entry, + which has a value. Annotations can be added to mailboxes when a + mailbox name is provided as the first argument to the SETMETADATA + command, or to the server as a whole when the empty string is + provided as the first argument to the command. + + For example, a general comment being added to a mailbox may have an + entry name of "/comment" and a value of "Really useful mailbox". + + The protocol changes to IMAP described below allow a client to access + or change the values of any annotation entry, assuming it has + sufficient access rights to do so. + +3.2. Namespace of Entries + + Each annotation is an entry that has a hierarchical name, with each + component of the name separated by a slash ("/"). An entry name MUST + NOT contain two consecutive "/" characters and MUST NOT end with a + "/" character. + + The value of an entry is NIL (has no value), or a string or binary + data of zero or more octets. A string MAY contain multiple lines of + text. Clients MUST use the CRLF (0x0D 0x0A) character octet sequence + to represent line ends in a multi-line string value. + + Entry names MUST NOT contain asterisk ("*") or percent ("%") + characters and MUST NOT contain non-ASCII characters or characters + with octet values in the range 0x00 to 0x19. Invalid entry names + result in a BAD response in any IMAP command in which they are used. + + Entry names are case-insensitive. + + Use of control or punctuation characters in entry names is strongly + discouraged. + + This specification defines an initial set of entry names available + for use with mailbox and server annotations. In addition, an + extension mechanism is described to allow additional names to be + added for extensibility. + + The first component in entry names defines the scope of the + annotation. Currently, only the prefixes "/private" or "/shared" are + defined. These prefixes are used to indicate whether an annotation + + + +Daboo Standards Track [Page 4] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + is stored on a per-user basis ("/private") and not visible to other + users, or whether an annotation is shared between authorized users + ("/shared") with a single value that can be read and changed by + authorized users with appropriate access. See Section 3.3 for + details. + + Entry names can have any number of components starting at 2, unless + they fall under the vendor namespaces (i.e., have a /shared/vendor/ + <vendor-token> or /private/vendor/<vendor-token> prefix as described + below), in which case they have at least 4 components. + +3.2.1. Entry Names + + Entry names MUST be specified in a Standards Track or IESG-approved + Experimental RFC, or fall under the vendor namespace. See + Section 6.1 for the registration template. + +3.2.1.1. Server Entries + + These entries are set or retrieved when the mailbox name argument to + the new SETMETADATA or GETMETADATA command is the empty string. + + /shared/comment + + Defines a comment or note that is associated with the server and + that is shared with authorized users of the server. + + /shared/admin + + Indicates a method for contacting the server administrator. The + value MUST be a URI (e.g., a mailto: or tel: URL). This entry is + always read-only -- clients cannot change it. It is visible to + authorized users of the system. + + /shared/vendor/<vendor-token> + + Defines the top level of shared entries associated with the + server, as created by a particular product of some vendor. This + entry can be used by vendors to provide server- or client-specific + annotations. The vendor-token MUST be registered with IANA, using + the Application Configuration Access Protocol (ACAP) [RFC2244] + vendor subtree registry. + + /private/vendor/<vendor-token> + + Defines the top level of private entries associated with the + server, as created by a particular product of some vendor. This + entry can be used by vendors to provide server- or client-specific + + + +Daboo Standards Track [Page 5] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + annotations. The vendor-token MUST be registered with IANA, using + the ACAP [RFC2244] vendor subtree registry. + +3.2.1.2. Mailbox Entries + + These entries are set or retrieved when the mailbox name argument to + the new SETMETADATA or GETMETADATA command is not the empty string. + + /shared/comment + + Defines a shared comment or note associated with a mailbox. + + /private/comment + + Defines a private (per-user) comment or note associated with a + mailbox. + + /shared/vendor/<vendor-token> + + Defines the top level of shared entries associated with a specific + mailbox, as created by a particular product of some vendor. This + entry can be used by vendors to provide client-specific + annotations. The vendor-token MUST be registered with IANA, using + the ACAP [RFC2244] vendor subtree registry. + + /private/vendor/<vendor-token> + + Defines the top level of private entries associated with a + specific mailbox, as created by a particular product of some + vendor. This entry can be used by vendors to provide client- + specific annotations. The vendor-token MUST be registered with + IANA, using the ACAP [RFC2244] vendor subtree registry. + +3.3. Private versus Shared and Access Control + + In the absence of the ACL (Access Control List) extension [RFC4314], + users can only set and retrieve private or shared mailbox annotations + on a mailbox that exists and is returned to them via a LIST or LSUB + command, and on which they have either read or write access to the + actual message content of the mailbox (as determined by the READ-ONLY + and READ-WRITE response codes as described in Section 5.2 of + [RFC4314]). + + When the ACL extension [RFC4314] is present, users can only set and + retrieve private or shared mailbox annotations on a mailbox on which + they have the "l" right and any one of the "r", "s", "w", "i", or "p" + rights. + + + + +Daboo Standards Track [Page 6] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + If a client attempts to set or retrieve annotations on mailboxes that + do not satisfy the conditions above, the server MUST respond with a + NO response. + + Users can always retrieve private or shared server annotations if + they exist. Servers MAY restrict the creation of private or shared + server annotations as appropriate. When restricted, the server MUST + return a NO response when the SETMETADATA command is used to try to + create a server annotation. + + If the METADATA extension is present, support for shared annotations + is REQUIRED, whilst support for private annotations is OPTIONAL. + This recognizes the fact that support for private annotations may + introduce significantly more complexity to a server in terms of + tracking ownership of the annotations, how quota is determined for + users based on their own annotations, etc. + +4. IMAP Protocol Changes + +4.1. General Considerations + + The new SETMETADATA command and the METADATA response each have a + mailbox name argument. An empty string is used for the mailbox name + to signify server annotations. A non-empty string is used to signify + mailbox annotations attached to the corresponding mailbox. + + Servers SHOULD ensure that mailbox annotations are automatically + moved when the mailbox they refer to is renamed, i.e., the + annotations follow the mailbox. This applies to a rename of the + INBOX, with the additional behavior that the annotations are copied + from the original INBOX to the renamed mailbox, i.e., mailbox + annotations are preserved on the INBOX when it is renamed. + + Servers SHOULD delete annotations for a mailbox when the mailbox is + deleted, so that a mailbox created with the same name as a previously + existing mailbox does not inherit the old mailbox annotations. + + Servers SHOULD allow annotations on all 'types' of mailboxes, + including ones reporting \Noselect for their LIST response. Servers + can implicitly remove \Noselect mailboxes when all child mailboxes + are removed, and, at that time any annotations associated with the + \Noselect mailbox SHOULD be removed. + + The server is allowed to impose limitations on the size of any one + annotation or the total number of annotations for a single mailbox or + for the server as a whole. However, the server MUST accept an + annotation data size of at least 1024 bytes, and an annotation count + per server or mailbox of at least 10. + + + +Daboo Standards Track [Page 7] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + Some annotations may be "read-only" -- i.e., they are set by the + server and cannot be changed by the client. Also, such annotations + may be "computed" -- i.e., the value changes based on underlying + properties of the mailbox or server. For example, an annotation + reporting the total size of all messages in the mailbox would change + as messages are added or removed. Or, an annotation containing an + IMAP URL for the mailbox would change if the mailbox was renamed. + + Servers MAY support sending unsolicited responses for use when + annotations are changed by some "third-party" (see Section 4.4). In + order to do so, servers MUST support the ENABLE command [RFC5161] and + MUST only send unsolicited responses if the client used the ENABLE + command [RFC5161] extension with the capability string "METADATA" or + "METADATA-SERVER" earlier in the session, depending on which of those + capabilities is supported by the server. + +4.2. GETMETADATA Command + + This extension adds the GETMETADATA command. This allows clients to + retrieve server or mailbox annotations. + + This command is only available in authenticated or selected state + [RFC3501]. + + Arguments: mailbox-name + options + entry-specifier + + Responses: required METADATA response + + Result: OK - command completed + NO - command failure: can't access annotations on + the server + BAD - command unknown or arguments invalid + + When the mailbox name is the empty string, this command retrieves + server annotations. When the mailbox name is not empty, this command + retrieves annotations on the specified mailbox. + + Options MAY be included with this command and are defined below. + + Example: + + C: a GETMETADATA "" /shared/comment + S: * METADATA "" (/shared/comment "Shared comment") + S: a OK GETMETADATA complete + + + + + +Daboo Standards Track [Page 8] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + In the above example, the contents of the value of the "/shared/ + comment" server entry is requested by the client and returned by + the server. + + Example: + + C: a GETMETADATA "INBOX" /private/comment + S: * METADATA "INBOX" (/private/comment "My own comment") + S: a OK GETMETADATA complete + + In the above example, the contents of the value of the "/private/ + comment" mailbox entry for the mailbox "INBOX" is requested by the + client and returned by the server. + + Entry specifiers can be lists of atomic specifiers, so that multiple + annotations may be returned in a single GETMETADATA command. + + Example: + + C: a GETMETADATA "INBOX" (/shared/comment /private/comment) + S: * METADATA "INBOX" (/shared/comment "Shared comment" + /private/comment "My own comment") + S: a OK GETMETADATA complete + + In the above example, the values of the two server entries + "/shared/comment" and "/private/comment" on the mailbox "INBOX" + are requested by the client and returned by the server. + +4.2.1. MAXSIZE GETMETADATA Command Option + + When the MAXSIZE option is specified with the GETMETADATA command, it + restricts which entry values are returned by the server. Only entry + values that are less than or equal in octet size to the specified + MAXSIZE limit are returned. If there are any entries with values + larger than the MAXSIZE limit, the server MUST include the METADATA + LONGENTRIES response code in the tagged OK response for the + GETMETADATA command. The METADATA LONGENTRIES response code returns + the size of the biggest entry value requested by the client that + exceeded the MAXSIZE limit. + + Example: + + C: a GETMETADATA "INBOX" (MAXSIZE 1024) + (/shared/comment /private/comment) + S: * METADATA "INBOX" (/private/comment "My own comment") + S: a OK [METADATA LONGENTRIES 2199] GETMETADATA complete + + + + + +Daboo Standards Track [Page 9] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + In the above example, the values of the two server entries + "/shared/comment" and "/private/comment" on the mailbox "INBOX" + are requested by the client, which wants to restrict the size of + returned values to 1024 octets. In this case, the "/shared/ + comment" entry value is 2199 octets and is not returned. + +4.2.2. DEPTH GETMETADATA Command Option + + When the DEPTH option is specified with the GETMETADATA command, it + extends the list of entry values returned by the server. For each + entry name specified in the GETMETADATA command, the server returns + the value of the specified entry name (if it exists), plus all + entries below the entry name up to the specified DEPTH. Three values + are allowed for DEPTH: + + "0" - no entries below the specified entry are returned + "1" - only entries immediately below the specified entry are returned + "infinity" - all entries below the specified entry are returned + + Thus, "depth 1" for an entry "/a" will match "/a" as well as its + children entries (e.g., "/a/b"), but will not match grandchildren + entries (e.g., "/a/b/c"). + + If the DEPTH option is not specified, this is the same as specifying + "DEPTH 0". + + Example: + + C: a GETMETADATA "INBOX" (DEPTH 1) + (/private/filters/values) + S: * METADATA "INBOX" (/private/filters/values/small + "SMALLER 5000" /private/filters/values/boss + "FROM \"boss@example.com\"") + S: a OK GETMETADATA complete + + In the above example, 2 entries below the /private/filters/values + entry exist on the mailbox "INBOX": "/private/filters/values/ + small" and "/private/filters/values/boss". + +4.3. SETMETADATA Command + + This extension adds the SETMETADATA command. This allows clients to + set annotations. + + This command is only available in authenticated or selected state + [RFC3501]. + + + + + +Daboo Standards Track [Page 10] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + Arguments: mailbox-name + entry + value + list of entry, values + + Responses: no specific responses for this command + + Result: OK - command completed + NO - command failure: can't set annotations, + or annotation too big or too many + BAD - command unknown or arguments invalid + + This command sets the specified list of entries by adding or + replacing the specified values provided, on the specified existing + mailboxes or on the server (if the mailbox argument is the empty + string). Clients can use NIL for the value of entries it wants to + remove. The server SHOULD NOT return a METADATA response containing + the updated annotation data. Clients MUST NOT assume that a METADATA + response will be sent, and MUST assume that if the command succeeds, + then the annotation has been changed. + + If the server is unable to set an annotation because the size of its + value is too large, the server MUST return a tagged NO response with + a "[METADATA MAXSIZE NNN]" response code when NNN is the maximum + octet count that it is willing to accept. + + If the server is unable to set a new annotation because the maximum + number of allowed annotations has already been reached, the server + MUST return a tagged NO response with a "[METADATA TOOMANY]" response + code. + + If the server is unable to set a new annotation because it does not + support private annotations on one of the specified mailboxes, the + server MUST return a tagged NO response with a "[METADATA NOPRIVATE]" + response code. + + When any one annotation fails to be set, resulting in a tagged NO + response from the server, then the server MUST NOT change the values + for other annotations specified in the SETMETADATA command. + + Example: + + C: a SETMETADATA INBOX (/private/comment {33} + S: + ready for data + My new comment across + two lines. + ) + S: a OK SETMETADATA complete + + + +Daboo Standards Track [Page 11] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + In the above example, the entry "/private/comment" for the mailbox + "INBOX" is created (if not already present) and the value set to a + multi-line string. + + Example: + + C: a SETMETADATA INBOX (/private/comment NIL) + S: a OK SETMETADATA complete + + In the above example, the entry "/private/comment" is removed from + the mailbox "INBOX". + + Multiple entries can be set in a single SETMETADATA command by + listing entry-value pairs in the list. + + Example: + + C: a SETMETADATA INBOX (/private/comment "My new comment" + /shared/comment "This one is for you!") + S: a OK SETMETADATA complete + + In the above example, the entries "/private/comment" and "/shared/ + comment" for the mailbox "INBOX" are created (if not already + present) and the values set as specified. + + Example: + + C: a SETMETADATA INBOX (/private/comment "My new comment") + S: a NO [METADATA TOOMANY] SETMETADATA failed + + In the above example, the server is unable to set the requested + (new) annotation as it has reached the limit on the number of + annotations it can support on the specified mailbox. + +4.4. METADATA Response + + The METADATA response displays results of a GETMETADATA command, or + can be returned as an unsolicited response at any time by the server + in response to a change in a server or mailbox annotation. + + When unsolicited responses are activated by the ENABLE [RFC5161] + command for this extension, servers MUST send unsolicited METADATA + responses if server or mailbox annotations are changed by a third- + party, allowing servers to keep clients updated with changes. + + Unsolicited METADATA responses MUST only contain entry names, not the + values. If the client wants to update any cached values, it must + explicitly retrieve those using a GETMETADATA command. + + + +Daboo Standards Track [Page 12] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + The METADATA response can contain multiple entries in a single + response, but the server is free to return multiple responses for + each entry or group of entries, if it desires. + + This response is only available in authenticated or selected state + [RFC3501]. + +4.4.1. METADATA Response with Values + + The response consists of a list of entry-value pairs. + + Example: + + C: a GETMETADATA "" /shared/comment + S: * METADATA "" (/shared/comment "My comment") + S: a OK GETMETADATA complete + + In the above example, a single entry with its value is returned by + the server. + + Example: + + C: a GETMETADATA "INBOX" /private/comment /shared/comment + S: * METADATA "INBOX" (/private/comment "My comment" + /shared/comment "Its sunny outside!") + S: a OK GETMETADATA complete + + In the above example, two entries and their values are returned by + the server. + + Example: + + C: a GETMETADATA "INBOX" /private/comment /shared/comment + S: * METADATA "INBOX" (/private/comment "My comment") + S: * METADATA "INBOX" (/shared/comment "Its sunny outside!") + S: a OK GETMETADATA complete + + In the above example, the server returns two separate responses + for each of the two entries requested. + +4.4.2. Unsolicited METADATA Response without Values + + The response consists of a list of entries, each of which have + changed on the server or mailbox. + + Example: + + + + + +Daboo Standards Track [Page 13] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + C: a NOOP + S: * METADATA "" /shared/comment + S: a OK NOOP complete + + In the above example, the server indicates that the "/shared/ + comment" server entry has been changed. + + Example: + + C: a NOOP + S: * METADATA "INBOX" /shared/comment /private/comment + S: a OK NOOP complete + + In the above example, the server indicates a change to two mailbox + entries. + +5. Formal Syntax + + The following syntax specification uses the Augmented Backus-Naur + Form (ABNF) notation as specified in [RFC5234]. + + Non-terminals referenced but not defined below are as defined by + [RFC3501], with the new definitions in [RFC4466] superseding those in + [RFC3501]. + + 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. + + capability =/ "METADATA" / "METADATA-SERVER" + ; defines the capabilities for this extension. + + command-auth =/ setmetadata / getmetadata + ; adds to original IMAP command + + entries = entry / + "(" entry *(SP entry) ")" + ; entry specifiers + + entry = astring + ; slash-separated path to entry + ; MUST NOT contain "*" or "%" + + entry-value = entry SP value + + entry-values = "(" entry-value *(SP entry-value) ")" + + + + +Daboo Standards Track [Page 14] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + entry-list = entry *(SP entry) + ; list of entries used in unsolicited + ; METADATA response + + getmetadata = "GETMETADATA" [SP getmetadata-options] + SP mailbox SP entries + ; empty string for mailbox implies + ; server annotation. + + getmetadata-options = "(" getmetadata-option + *(SP getmetadata-option) ")" + + getmetadata-option = tagged-ext-label [SP tagged-ext-val] + ; tagged-ext-label and tagged-ext-val + ; are defined in [RFC4466]. + + maxsize-opt = "MAXSIZE" SP number + ; Used as a getmetadata-option + + metadata-resp = "METADATA" SP mailbox SP + (entry-values / entry-list) + ; empty string for mailbox implies + ; server annotation. + + response-payload =/ metadata-resp + ; adds to original IMAP data responses + + resp-text-code =/ "METADATA" SP "LONGENTRIES" SP number + ; new response codes for GETMETADATA + + resp-text-code =/ "METADATA" SP ("MAXSIZE" SP number / + "TOOMANY" / "NOPRIVATE") + ; new response codes for SETMETADATA + ; failures + + scope-opt = "DEPTH" SP ("0" / "1" / "infinity") + ; Used as a getmetadata-option + + setmetadata = "SETMETADATA" SP mailbox + SP entry-values + ; empty string for mailbox implies + ; server annotation. + + value = nstring / literal8 + + + + + + + +Daboo Standards Track [Page 15] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +6. IANA Considerations + + All entries MUST have either "/shared" or "/private" as a prefix. + Entry names MUST be specified in a Standards Track or IESG-approved + Experimental RFC, or fall under the vendor namespace (i.e., use + /shared/vendor/<vendor-token> or /private/vendor/<vendor-token> as + the prefix). + + Each entry registration MUST include a content-type that is used to + indicate the nature of the annotation value. Where applicable, a + charset parameter MUST be included with the content-type. + +6.1. Entry and Attribute Registration Template + + To: iana@iana.org + Subject: IMAP METADATA Entry Registration + + Type: [Either "Mailbox" or "Server"] + + Name: [the name of the entry] + + Description: [a description of what the entry is for] + + Content-type: [MIME Content-Type and charset for the entry value] + + RFC Number: [for entries published as RFCs] + + Contact: [email and/or physical address to contact for + additional information] + +6.2. Server Entry Registrations + + The following templates specify the IANA registrations of annotation + entries specified in this document. + + + + + + + + + + + + + + + + + +Daboo Standards Track [Page 16] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +6.2.1. /shared/comment + + To: iana@iana.org + Subject: IMAP METADATA Entry Registration + + Type: Server + + Name: /shared/comment + + Description: Defines a comment or note that is associated + with the server and that is shared with + authorized users of the server. + + Content-type: text/plain; charset=utf-8 + + RFC Number: RFC 5464 + + Contact: IMAP Extensions mailto:ietf-imapext@imc.org + +6.2.2. /shared/admin + + To: iana@iana.org + Subject: IMAP METADATA Entry Registration + + Type: Server + + Name: /shared/admin + + Description: Indicates a method for contacting the server + administrator. The value MUST be a URI (e.g., a + mailto: or tel: URL). This entry is always + read-only -- clients cannot change it. It is visible + to authorized users of the system. + + Content-type: text/plain; charset=utf-8 + + RFC Number: RFC 5464 + + Contact: IMAP Extensions mailto:ietf-imapext@imc.org + +6.3. Mailbox Entry Registrations + + The following templates specify the IANA registrations of annotation + entries specified in this document. + + + + + + + +Daboo Standards Track [Page 17] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +6.3.1. /shared/comment + + To: iana@iana.org + Subject: IMAP METADATA Entry Registration + + Type: Mailbox + + Name: /shared/comment + + Description: Defines a shared comment or note associated with a + mailbox. + + Content-type: text/plain; charset=utf-8 + + RFC Number: RFC 5464 + + Contact: IMAP Extensions mailto:ietf-imapext@imc.org + +6.3.2. /private/comment + + To: iana@iana.org + Subject: IMAP METADATA Entry Registration + + Type: Mailbox + + Name: /private/comment + + Description: Defines a private comment or note associated with a + mailbox. + + Content-type: text/plain; charset=utf-8 + + RFC Number: RFC 5464 + + Contact: IMAP Extensions mailto:ietf-imapext@imc.org + +7. Security Considerations + + The security considerations in Section 11 of [RFC3501] apply here + with respect to protecting annotations from snooping. Servers MAY + choose to only support the METADATA and/or METADATA-SERVER extensions + after a privacy layer has been negotiated by the client. + + Annotations can contain arbitrary data of varying size. As such, + servers MUST ensure that size limits are enforced to prevent a user + from using up all available space on a server and preventing use by + others. Clients MUST treat annotation data values as an "untrusted" + source of data as it is possible for it to contain malicious content. + + + +Daboo Standards Track [Page 18] + +RFC 5464 The IMAP METADATA Extension February 2009 + + + Annotations whose values are intended to remain private MUST be + stored only in entries that have the "/private" prefix on the entry + name. + + Excluding the above issues, the METADATA extension does not raise any + security considerations that are not present in the base IMAP + protocol, and these issues are discussed in [RFC3501]. + +8. Normative References + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + [RFC2244] Newman, C. and J. Myers, "ACAP -- Application + Configuration Access Protocol", RFC 2244, November 1997. + + [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION + 4rev1", RFC 3501, March 2003. + + [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", + RFC 4314, December 2005. + + [RFC4466] Melnikov, A. and C. Daboo, "Collected Extensions to IMAP4 + ABNF", RFC 4466, April 2006. + + [RFC5161] Gulbrandsen, A. and A. Melnikov, "The IMAP ENABLE + Extension", RFC 5161, March 2008. + + [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax + Specifications: ABNF", STD 68, RFC 5234, January 2008. + +Appendix A. Acknowledgments + + The ideas expressed in this document are based on the message + annotation document that was co-authored by Randall Gellens. The + author would like to thank the following individuals for contributing + their ideas and support for writing this specification: Dave + Cridland, Arnt Gulbrandsen, Dan Karp, Alexey Melnikov, Ken Murchison, + Chris Newman, and Michael Wener. + + + + + + + + + + + + +Daboo Standards Track [Page 19] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +Author's Address + + Cyrus Daboo + Apple Inc. + 1 Infinite Loop + Cupertino, CA 95014 + USA + + EMail: cyrus@daboo.name + URI: http://www.apple.com/ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Daboo Standards Track [Page 20] + +RFC 5464 The IMAP METADATA Extension February 2009 + + +Full Copyright Statement + + Copyright (C) The IETF Trust (2009). + + 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. + + 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, THE IETF TRUST 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. + +Intellectual Property + + 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. + + + + + + + + + + + + +Daboo Standards Track [Page 21] + + |