JMAP                                                          N. Jenkins
Internet-Draft                                                  FastMail
Updates: 5788 (if approved)                             October 30,                            November 29, 2017
Intended status: Standards Track
Expires: May 3, June 2, 2018

                             JMAP for Mail
                        draft-ietf-jmap-mail-02
                        draft-ietf-jmap-mail-03

Abstract

   This document specifies a data model for synchronising email data
   with a server using JMAP.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 3, June 2, 2018.

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   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   3
     1.2.  The Date datatypes  . . . . . . . . . . . . . . . . . . .   4
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.3.
     1.4.  Addition to the capabilities object . . . . . . . . . . .   4
   2.  Mailboxes . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  getMailboxes  . . . . . . . . . . . . . . . . . . . . . .   8
     2.2.  getMailboxUpdates . . . . . . . . . . . . . . . . . . . .   8
     2.3.  getMailboxList  . . . . . . . . . . . . . . . . . . . . .   8   9
     2.4.  getMailboxListUpdates . . . . . . . . . . . . . . . . . .   9
     2.5.  setMailboxes  . . . . . . . . . . . . . . . . . . . . . .   9
   3.  Threads . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     3.1.  getThreads  . . . . . . . . . . . . . . . . . . . . . . .  10  11
       3.1.1.  Example . . . . . . . . . . . . . . . . . . . . . . .  11
     3.2.  getThreadUpdates  . . . . . . . . . . . . . . . . . . . .  11
   4.  Messages  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     4.1.  getMessages . . . . . . . . . . . . . . . . . . . . . . .  16
       4.1.1.  Example . . . . . . . . . . . . . . . . . . . . . . .  17
     4.2.  getMessageUpdates . . . . . . . . . . . . . . . . . . . .  17
     4.3.  getMessageList  . . . . . . . . . . . . . . . . . . . . .  17  18
       4.3.1.  Filtering . . . . . . . . . . . . . . . . . . . . . .  17  18
       4.3.2.  Sorting . . . . . . . . . . . . . . . . . . . . . . .  20  21
       4.3.3.  Thread collapsing . . . . . . . . . . . . . . . . . .  21  22
       4.3.4.  Response  . . . . . . . . . . . . . . . . . . . . . .  21  22
     4.4.  getMessageListUpdates . . . . . . . . . . . . . . . . . .  22
     4.5.  setMessages . . . . . . . . . . . . . . . . . . . . . . .  22
     4.6.  importMessages  . . . . . . . . . . . . . . . . . . . . .  23
     4.7.  copyMessages  . . . . . . . . . . . . . . . . . . . . . .  25
   5.  MessageSubmission . . . . . . . . . . . . . . . . . . . . . .  27
     5.1.  getMessageSubmissions . . . . . . . . . . . . . . . . . .  31  32
     5.2.  getMessageSubmissionUpdates . . . . . . . . . . . . . . .  31  32
     5.3.  getMessageSubmissionList  . . . . . . . . . . . . . . . .  31  32
     5.4.  getMessageSubmissionListUpdates . . . . . . . . . . . . .  32  33
     5.5.  setMessageSubmissions . . . . . . . . . . . . . . . . . .  32  33
   6.  Identities  . . . . . . . . . . . . . . . . . . . . . . . . .  34  35
     6.1.  getIdentities . . . . . . . . . . . . . . . . . . . . . .  35  36
     6.2.  getIdentityUpdates  . . . . . . . . . . . . . . . . . . .  35  36
     6.3.  setIdentities . . . . . . . . . . . . . . . . . . . . . .  35  36
   7.  SearchSnippets  . . . . . . . . . . . . . . . . . . . . . . .  36
     7.1.  getSearchSnippets . . . . . . . . . . . . . . . . . . . .  36  37
   8.  Vacation Response . . . . . . . . . . . . . . . . . . . . . .  38
     8.1.  getVacationResponse . . . . . . . . . . . . . . . . . . .  39
     8.2.  setVacationResponse . . . . . . . . . . . . . . . . . . .  39
   9.  Security considerations . . . . . . . . . . . . . . . . . . .  39
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  39
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  39
     10.2.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  41  42
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  41  42

1.  Introduction

   JMAP is a generic protocol for synchronising data, such as mail,
   calendars or contacts, between a client and a server.  It is
   optimised for mobile and web environments, and aims to provide a
   consistent interface to different data types.

   This specification defines a data model for synchronising mail
   between a client and a server using JMAP.

1.1.  Notational Conventions

   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].

   The underlying format used for this specification is I-JSON
   ([RFC7493]).  Consequently, the terms "object" and "array" as well as
   the four primitive types (strings, numbers, booleans, and null) are
   to be interpreted as described in Section 1 of [RFC7159].  Unless
   otherwise noted, all the property names and values are case
   sensitive.

   Some examples in this document contain "partial" JSON documents used
   for illustrative purposes.  In these examples, three periods "..."
   are used to indicate a portion of the document that has been removed
   for compactness.

   Types signatures are given for all JSON objects in this document.
   The following conventions are used:

   o  "Boolean|String" - The value is either a JSON "Boolean" value, or
      a JSON "String" value.

   o  "Foo" - Any name that is not a native JSON type means an object
      for which the properties (and their types) are defined elsewhere
      within this document.

   o  "Foo[]" - An array of objects of type "Foo".

   o  "String[Foo]" - A JSON "Object" being used as a map (associative
      array), where all the values are of type "Foo".

   Object properties may also have a set of attributes defined along
   with the type signature.  These have the following meanings:

   o  *sever-set*: Only the server can set the value for this property.
      The client MUST NOT send this property when creating a new object
      of this type.

   o  *immutable*: The value MUST NOT change after the object is
      created.

   o  *default*: (This is followed by a JSON value).  The value that
      will be used for this property if it is omitted when creating a
      new object of this type.

1.2.  The Date datatypes

   Where "Date" is given as a type, it means a string in [RFC3339]
   _date-time_ format.  To ensure a normalised form, the _time-secfrac_
   MUST always be omitted and any letters in the string (e.g.  "T" and
   "Z") MUST be upper-case.  For example, ""2014-10-30T14:12:00+08:00"".

   Where "UTCDate" is given as a type, it means a "Date" where the
   _time-offset_ component MUST be "Z" (i.e. it must be in UTC time).
   For example, ""2014-10-30T06:12:00Z"".

1.3.  Terminology

   The same terminology is used in this document as in the core JMAP
   specification.

1.3.

1.4.  Addition to the capabilities object

   The capabilities object is returned as part of the standard JMAP
   session object; see the JMAP spec.  Servers supporting _this_
   specification MUST add a property called "{TODO: URI for this spec}" "ietf:jmapmail" to the
   capabilities object.  The value of this property is an object which SHOULD
   MUST contain the following information on server capabilities:

   o  *maxMailboxesPerMessage*: "Number|null" The maximum number of
      mailboxes that can be can assigned to a single message.  This MUST
      be an integer >= 1, or "null" for no limit (or rather, the limit
      is always the number of mailboxes in the account).

   o  *maxSizeMessageAttachments*:  *maxSizeAttachmentsPerMessage*: "Number" The maximum total size of
      attachments, in bytes, allowed for messages. a single message.  A server MAY
      still reject messages with a lower attachment size total (for
      example, if the body includes several megabytes of text, causing
      the size of the encoded MIME structure to be over some server-defined server-
      defined limit).

   o  *maxDelayedSend*: "Number" The number in seconds of the maximum
      delay the server supports in sending (see the MessageSubmission
      object).  This is "0" if the server does not support delayed send.

   o  *messageListSortOptions*: "String[]" A list of all the message
      properties the server supports for sorting by.  This MAY include
      properties the client does not recognise (for example custom
      properties specified in a vendor extension).  Clients MUST ignore
      any unknown properties in the list.

   o  *submissionExtensions*: "String[String[]]" A JMAP implementation
      that talks to a Submission [RFC6409] server SHOULD have a
      configuration setting that allows an administrator to expose a new
      submission EHLO capability in this field.  This allows a JMAP
      server to gain access to a new submission extension without code
      changes.  By default, the JMAP server should show only known safe-
      to-expose EHLO capabilities in this field, and hide EHLO
      capabilites
      capabilities that are only relevant to the JMAP server.  Each key
      in the object is the _ehlo-name_, and the value is a list of
      _ehlo-args_.  Examples of safe-to-expose Submission extensions
      include:

      *  FUTURERELEASE ([RFC4865])

      *  SIZE ([RFC1870])

      *  DSN ([RFC3461])

      *  DELIVERYBY ([RFC2852])

      *  MT-PRIORITY ([RFC6710])

      A JMAP server MAY advertise an extension and implement the
      semantics of that extension locally on the JMAP server even if a
      submission server used by JMAP doesn't implement it.  The full
      IANA registry of submission extensions can be found at
      <https://www.iana.org/assignments/mail-parameters/mail-
      parameters.xhtml#mail-parameters-2>

2.  Mailboxes

   A mailbox represents a named set of emails.  This is the primary
   mechanism for organising messages within an account.  It is analogous
   to a folder or a label in other systems.  A mailbox may perform a
   certain role in the system; see below for more details.

   For compatibility with IMAP, a message MUST belong to one or more
   mailboxes.  The message id does not change if the message changes
   mailboxes.

   A *Mailbox* object has the following properties:

   o  *id*: "String" (immutable; server-set) The id of the mailbox.

   o  *name*: "String" User-visible name for the mailbox, e.g.  "Inbox".
      This may be any UTF-8 string ([RFC3629]) of at least 1 character
      in length and maximum 256 bytes in size.  Servers SHOULD forbid
      sibling Mailboxes with the same name.

   o  *parentId*: "String|null" (default: "null") The mailbox id for the
      parent of this mailbox, or "null" if this mailbox is at the top
      level.  Mailboxes form acyclic graphs (forests) directed by the
      child-to-parent relationship.  There MUST NOT be a loop.

   o  *role*: "String|null" (default: "null") Identifies system
      mailboxes.  This property can only be set on create.  After the
      record has been created, this property is immutable.  The
      following values MUST be used for the relevant mailboxes:

      *  "inbox" - the mailbox to which new mail is delivered by
         default, unless diverted by a rule or spam filter etc.

      *  "archive" - messages the user does not need right now, but does
         not wish to delete.

      *  "drafts" - messages the user is currently writing and are not
         yet sent.

      *  "sent" - messages the user has sent.

      *  "trash" - messages the user has deleted.

      *  "spam" - messages considered spam by the server.

      *  "templates" - drafts which should be used as templates (i.e.
         used as the basis for creating new drafts).

      No two mailboxes may have the same role.  Mailboxes without a
      known purpose MUST have a role of "null".  An account is not
      required to have mailboxes with any of the above roles.  A client
      MAY create new mailboxes with a role property to help them keep
      track of a use-case not covered by the above list.  To avoid
      potential conflict with any special behaviour a server might apply
      to mailboxes with certain roles in the future, any roles not in
      the above list created by the client must begin with ""x-"".  The
      client MAY attempt to create mailboxes with the standard roles if
      not already present, but the server MAY reject these.

   o  *sortOrder*: "Number" (default: "0") Defines the sort order of
      mailboxes when presented in the client's UI, so it is consistent
      between devices.  The number MUST be an integer in the range 0 <=
      sortOrder < 2^31.  A mailbox with a lower order should be
      displayed before a mailbox with a higher order (that has the same
      parent) in any mailbox listing in the client's UI.  Mailboxes with
      equal order SHOULD be sorted in alphabetical order by name.  The
      sorting SHOULD take into account locale-specific character order
      convention.

   o  *mayReadItems*: "Boolean" (server-set) If true, may use this
      mailbox as part of a filter in a _getMessageList_ call.  If a
      submailbox sub-
      mailbox is shared but not the parent mailbox, this may be "false".

   o  *mayAddItems*: "Boolean" (server-set) The user may add messages to
      this mailbox (by either creating a new message or moving an
      existing one).

   o  *mayRemoveItems*: "Boolean" (server-set) The user may remove
      messages from this mailbox (by either changing the mailboxes of a
      message or deleting it).

   o  *mayCreateChild*: "Boolean" (server-set) The user may create a
      mailbox with this mailbox as its parent.

   o  *mayRename*: "Boolean" (server-set) The user may rename the
      mailbox or make it a child of another mailbox.

   o  *mayDelete*: "Boolean" (server-set) The user may delete the
      mailbox itself.

   o  *totalMessages*: "Number" (server-set) The number of messages in
      this mailbox.

   o  *unreadMessages*: "Number" (server-set) The number of messages in
      this mailbox that have neither the "$Seen" keyword nor the
      "$Draft" keyword.

   o  *totalThreads*: "Number" (server-set) The number of threads where
      at least one message in the thread is in this mailbox.

   o  *unreadThreads*: "Number" (server-set) The number of threads where
      at least one message in the thread has neither the "$Seen" keyword
      nor the "$Draft" keyword AND at least one message in the thread is
      in this mailbox (but see below for special case handling of
      Trash).  Note, the unread message does not need to be the one in
      this mailbox.

   The Trash mailbox (that is a mailbox with "role == "trash"") MUST be
   treated specially for the purpose of unread counts:

   1.  Messages that are *only* in the Trash (and no other mailbox) are
       ignored when calculating the "unreadThreads" count of other
       mailboxes.

   2.  Messages that are *not* in the Trash are ignored when calculating
       the "unreadThreads" count for the Trash mailbox.

   The result of this is that messages in the Trash are treated as
   though they are in a separate thread for the purposes of unread
   counts.  It is expected that clients will hide messages in the Trash
   when viewing a thread in another mailbox and vice versa.  This allows
   you to delete a single message to the Trash out of a thread.

   So for example, suppose you have an account where the entire contents
   is a single conversation with 2 messages: an unread message in the
   Trash and a read message in the Inbox.  The "unreadThreads" count
   would be "1" for the Trash and "0" for the Inbox.

   For IMAP compatibility, a message in both the Trash and another
   mailbox SHOULD be treated by the client as existing in both places
   (i.e. when emptying the trash, the client SHOULD just remove the
   Trash mailbox and leave it in the other mailbox).

   The following JMAP methods are supported:

2.1.  getMailboxes

   Standard _getFoos_ method.  The _ids_ argument may be "null" to fetch
   all at once.

2.2.  getMailboxUpdates

   Standard _getFooUpdates_ method, but with one extra argument to the
   _mailboxUpdates_ response:

   o  *changedProperties*: "String[]|null" If only the mailbox counts
      (unread/total messages/threads) have changed since the old state,
      this will be the list of properties that may have changed, i.e.
      "["totalMessages", "unreadMessages", "totalThreads",
      "unreadThreads"]".  If the server is unable to tell if only counts
      have changed, it MUST just be "null".

   Since counts frequently change but the rest of the mailboxes state
   for most use cases changes rarely, the server can help the client
   optimise data transfer by keeping track of changes to message counts
   separately to other state changes.  The _changedProperties_ array may
   be used directly via a result reference in a subsequent getMailboxes
   call in a single request.

2.3.  getMailboxList

   Standard _getFooList_ method.

   The *FilterCondition* object (optionally passed as the _filter_
   argument) has the following properties, any of which may be omitted:

   o  *parentId*: "String|null" The Mailbox _parentId_ property must
      match the given value exactly.

   o  *hasRole*: "Boolean" If this is "true", a Mailbox matches if it
      has a non-"null" value for its _role_ property.

   A Mailbox object matches the filter if and only if all of the given
   conditions given match.  If zero properties are specified, it is
   automatically "true" for all objects.

   The following properties MUST be supported for sorting:

   o  "sortOrder"

   o  "name"

2.4.  getMailboxListUpdates

   Standard _getFooListUpdates_ method.

2.5.  setMailboxes

   Standard _setFoos_ method.  The following extra _SetError_ types are
   defined:

   For *create*:

   o  "maxQuotaReached": The user has reached a server-defined limit on
      the number of mailboxes.

   For *update*:

   o  "forbidden": The update would violate a mayXXX property.

   For *destroy*:

   o  "forbidden": The update would violate a mayXXX property.

   o  "mailboxHasChild": The mailbox still has at least one child
      mailbox.  The client MUST remove these before it can delete the
      parent mailbox.

   o  "mailboxHasMessage": The mailbox has at least one message assigned
      to it.  The client MUST remove these before it can delete the
      mailbox.

3.  Threads

   Replies are grouped together with the original message to form a
   thread.  In JMAP, a thread is simply a flat list of messages, ordered
   by date.  Every message MUST belong to a thread, even if it is the
   only message in the thread.

   The JMAP spec does not require the server to use any particular
   algorithm for determining whether two messages belong to the same
   thread, however there is a recommended algorithm in the
   implementation guide [1].

   If messages are delivered out of order for some reason, a user may
   receive two messages in the same thread but without headers that
   associate them with each other.  The arrival of a third message in
   the thread may provide the missing references to join them all
   together into a single thread.  Since the "threadId" of a message is
   immutable, if the server wishes to merge the threads, it MUST handle
   this by deleting and reinserting (with a new message id) the messages
   that change threadId.

   A *Thread* object has the following properties:

   o  *id*: "String" (immutable) The id of the thread.

   o  *messageIds*: "String[]" The ids of the messages in the thread,
      sorted such that:

      *  Any message with the "$Draft" keyword that has an "In-Reply-To"
         header is sorted after the _first_ non-draft message in the
         thread with the corresponding "Message-Id" header, but before
         any subsequent non-draft messages.

      *  Other than that, everything is sorted in _date_ order (as
         determined by the _receivedAt_ date property on
         of the _Message_ object), message, oldest first.

      *  If two messages are identical under the above two conditions,
         the sort is server-dependent but MUST be stable (sorting by id
         is recommended).

   The following JMAP methods are supported:

3.1.  getThreads

   Standard _getFoos_ method.

3.1.1.  Example

   Request:

                      [ "getThreads", {
                        "ids": ["f123u4", "f41u44"],
                      }, "#1" ]

   with response:

                [ "threads", {
                  "accountId": "acme",
                  "state": "f6a7e214",
                  "list": [
                    {
                      "id": "f123u4",
                      "messageIds": [ "eaa623", "f782cbb"]
                    },
                    {
                      "id": "f41u44",
                      "messageIds": [ "82cf7bb" ]
                    }
                  ],
                  "notFound": null
                }, "#1" ]

3.2.  getThreadUpdates

   Standard _getFooUpdates_ method.

4.  Messages

   A *Message* object is a JSON representation of an [RFC5322] message
   that hides the complexities of MIME.  All special encodings of either
   headers or textual body parts, such as Base64 ([RFC4648]), or
   [RFC2047] encoding of non-ASCII characters, MUST be fully decoded
   into UTF-8.  It has the following properties:

   o  *id*: "String" (immutable; server-set) The id of the message.
      This is the JMAP id, NOT the [RFC5322] Message-Id header.

   o  *blobId*: "String" (immutable; server-set) The id representing the
      raw [RFC5322] message.  This may be used to download the original
      message or to attach it directly to another message etc.

   o  *threadId*: "String" (immutable; server-set) The id of the thread
      to which this message belongs.

   o  *mailboxIds*: "String[Boolean]" The set of mailbox ids this
      message is in.  A message MUST belong to one or more mailboxes at
      all times (until it is deleted).  The set is represented as an
      object, with each key being a _Mailbox id_. The value for each key
      in the object MUST be "true".

   o  *keywords*: "String[Boolean]" (default: "{}") A set of keywords
      that apply to the message.  The set is represented as an object,
      with the keys being the _keywords_. The value for each key in the
      object MUST be "true".  Keywords are shared with IMAP.  The six
      system keywords from IMAP are treated specially.  The following
      four keywords have their first character changed from "\" in IMAP
      to "$" in JMAP and have particular semantic meaning:

      *  "$Draft": The message is a draft the user is composing.

      *  "$Seen": The message has been read.

      *  "$Flagged": The message has been flagged for urgent/special
         attention.

      *  "$Answered": The message has been replied to.

      The IMAP "\Recent" keyword is not exposed via JMAP.  The IMAP
      "\Deleted" keyword is also not present: IMAP uses a delete+expunge
      model, which JMAP does not.  Any message with the "\Deleted"
      keyword MUST NOT be visible via JMAP.  Users may add arbitrary
      keywords to a message.  For compatibility with IMAP, a keyword is
      a (case-sensitive) string of 1-255 characters in the ASCII subset
      %x21-%x7e (excludes control chars and space), and MUST NOT include
      any of these characters: "( ) { ] % * " \" The IANA Keyword
      Registry [2] as established in [RFC5788] assigns semantic meaning
      to some other keywords in common use.  New keywords may be
      established here in the future.  In particular, note:

      *  "$Forwarded": The message has been forwarded.

      *  "$Phishing": The message is highly likely to be phishing.
         Clients SHOULD warn users to take care when viewing this
         message and disable links and attachments.

      *  "$Junk": The message is definitely spam.  Clients SHOULD set
         this flag when users report spam to help train automated spam-
         detection systems.

      *  "$NotJunk": The message is definitely not spam.  Clients SHOULD
         set this flag when users indicate a message is legitimate, to
         help train automated spam-detection systems.

   o  *hasAttachment*: "Boolean" (immutable; server-set) This is "true"
      if and only if the _attachments_ property for the Message contains
      at least one entry where _isInline_ is "false".

   o  *headers*: "String[String]" (immutable; default: "{}") A map of
      lower-cased header name to (decoded) header value for all headers
      in the message.  For headers that occur multiple times (e.g.
      "Received"), the values are concatenated with a single new line
      ("\n") character in between each one.

   o  *sender*: "Emailer|null" (immutable; default: "null") An Emailer
      object (see below) containing the name/email from the parsed
      "Sender" header of the email.  If the email doesn't have a
      "Sender" header, this is "null".

   o  *from*: "Emailer[]|null" (immutable; default: "null") An array of
      name/email objects (see below) representing the parsed "From"
      header of the email, in the same order as they appear in the
      header.  If the email doesn't have a "From" header, this is
      "null".  If the header exists but does not have any content, the
      response is an array of zero length.

   o  *to*: "Emailer[]|null" (immutable; default: "null") An array of
      name/email objects (see below) representing the parsed "To" header
      of the email, in the same order as they appear in the header.  If
      the email doesn't have a "To" header, this is "null".  If the
      header exists but does not have any content, the response is an
      array of zero length.

   o  *cc*: "Emailer[]|null" (immutable; default: "null") An array of
      name/email objects (see below) representing the parsed "Cc" header
      of the email, in the same order as they appear in the header.  If
      the email doesn't have a "Cc" header, this is "null".  If the
      header exists but does not have any content, the response is an
      array of zero length.

   o  *bcc*: "Emailer[]|null" (immutable; default: "null") An array of
      name/email objects (see below) representing the parsed "Bcc"
      header of the email.  If the email doesn't have a "Bcc" header
      (which will be true for most emails outside of the Sent mailbox),
      this is "null".  If the header exists but does not have any
      content, the response is an array of zero length.

   o  *replyTo*: "Emailer[]|null" (immutable; default: "null") An array
      of name/email objects (see below) representing the parsed "Reply-
      To" header of the email, in the same order as they appear in the
      header.  If the email doesn't have a "Reply-To" header, this is
      "null".  If the header exists but does not have any content, the
      response is an array of zero length.

   o  *subject*: "String" (immutable; default: """") The subject of the
      message.  If none, defaults to the empty string, not "null".

   o  *date*:  *sentAt*: "Date" (immutable; default: time of creation on server)
      The parsed date from the message's _Date_ header.

   o  *receivedAt*: "UTCDate" (immutable; default: time of creation on
      server) The date the message was sent (or saved, if received by the message store.
      This is a
      draft). the _internal date_ in IMAP.

   o  *size*: "Number" (immutable; server-set) The size in bytes of the
      whole message as counted by the server towards the user's quota.

   o  *preview*: "String" (immutable; server-set) Up to 256 characters
      of the beginning of a plain text version of the message body.
      This is intended to be shown as a preview line on a mailbox
      listing, and the server may choose to skip quoted sections or
      salutations to return a more useful preview.

   o  *textBody*: "String" (immutable; default: """") The plain text
      body part for the message.  If there is only an HTML version of
      the body, a plain text version MUST be generated from this; the
      exact method of conversion in this case is not defined and is
      server-specific.  If there is neither a "text/plain" nor a "text/
      html" body part, this MUST be the empty string.

   o  *htmlBody*: "String|null" (immutable; default: "null") The HTML
      body part for the message if present.

   o  *attachments*: "Attachment[]|null" (default: "null") An array of
      attachment objects (see below) detailing all the attachments to
      the message.

   o  *attachedMessages*: "String[Message]|null" (immutable; server-set)
      An object mapping attachment id (as found in the "attachments"
      property) to a *Message* object with the following properties, for
      each [RFC5322] message attached to this one:

      *  headers

      *  from

      *  to

      *  cc

      *  bcc

      *  replyTo

      *  subject

      *  date

      *  textBody

      *  htmlBody

      *  attachments

      *  attachedMessages

      This property is set by the server based on the _attachments_
      property.

   An *Emailer* object has the following properties:

   o  *name*: "String" The name of the sender/recipient.  If a name
      cannot be extracted for an email, this property SHOULD be the
      empty string.

   o  *email*: "String" The email address of the sender/recipient.  This
      MUST be of the form ""<mailbox>@<host>"" If a "host" or even
      "mailbox" cannot be extracted for an email, the empty string
      SHOULD be used for this part (so the result MUST always still
      contain an ""@"" character).

   Group information and comments from the RFC 5322 header MUST be
   discarded when converting into an Emailer object.

   Example array of Emailer objects:

            [
                {name:"Joe Bloggs", email:"joeb@example.com"},
                {name:"", email:"john@example.com"},
                {name:"John Smith", email: "john@"}
            ]

   An *Attachment* object has the following properties:

   o  *blobId*: "String" The id of the binary data.

   o  *type*: "String" The content-type of the attachment.

   o  *name*: "String|null" The full file name, e.g.
      "myworddocument.doc", if available.

   o  *size*: "Number" The size, in bytes, of the attachment when fully
      decoded (i.e. the number of bytes in the file the user would
      download).

   o  *cid*: "String|null" The id used within the message body to
      reference this attachment.  This is only unique when paired with
      the message id, and has no meaning without reference to that.

   o  *isInline*: "Boolean" True if the attachment is referenced by a
      "cid:" link from within the HTML body of the message.

   o  *width*: "Number|null" (optional, server MAY omit if not
      supported) The width (in px) of the image, if the attachment is an
      image.

   o  *height*: "Number|null" (optional, server MAY omit if not
      supported) The height (in px) of the image, if the attachment is
      an image.

   To add an attachment, the file must first be uploaded using the
   standard upload mechanism; this will give the client a blobId that
   may be used to identify the file.  The "cid" property may be assigned
   by the client, and is solely used for matching up with "cid:<id>"
   links inside the "htmlBody".

   The following JMAP methods are supported:

4.1.  getMessages

   Standard _getFoos_ method, except the client may use the following
   pseudo values in the _properties_ argument:

   o  *body*: If ""body"" is included in the list of requested
      properties, it MUST be interpreted by the server as a request for
      ""htmlBody"" if the message has an HTML part, or ""textBody""
      otherwise.

   o  *headers.property*: Instead of requesting all the headers (by
      requesting the ""headers"" property, the client may specify the
      particular headers it wants using the "headers.property-name"
      syntax, e.g. ""headers.x-spam-score", "headers.x-spam-hits"").
      The server MUST return a _headers_ property but with just the
      requested headers in the object rather than all headers.  If
      ""headers"" is requested, the server MUST ignore the individual
      header requests and just return all headers.  If a requested
      header is not present in the message, it MUST NOT be present in
      the _headers_ object.  Header names are case-insensitive.

4.1.1.  Example

   Request:

 ["getMessages", {
   "ids": [ "f123u456", "f123u457" ],
   "properties": [ "threadId", "mailboxIds", "from", "subject", "date" ]
 }, "#1"]

   and response:

       ["messages", {
         "accountId": "abc",
         "state": "41234123231",
         "list": [
           {
             id: "f123u457",
             threadId: "ef1314a",
             mailboxIds: { "f123": true },
             from: [{name: "Joe Bloggs", email: "joe@bloggs.com"}],
             subject: "Dinner on Thursday?",
             date: "2013-10-13T14:12:00Z"
           }
         ],
         notFound: [ "f123u456" ]
       }, "#1"]

4.2.  getMessageUpdates

   Standard _getFooUpdates_ method.

4.3.  getMessageList

   Standard _getFooList_ method, but with the following additional
   arguments:

   o  *collapseThreads*: "Boolean" (default: "false") If "true",
      messages in the same thread as a previous message in the list
      (given the filter and sort order) will be removed from the list.
      This means at most only one message will be included in the list
      for any given thread.

4.3.1.  Filtering

   A *FilterOperator* object has the following properties:

   o  *operator*: "String" This MUST be one of the following strings:
      "AND"/"OR"/"NOT":

      *  *AND*: all of the conditions must match for the filter to
         match.

      *  *OR*: at least one of the conditions must match for the filter
         to match.

      *  *NOT*: none of the conditions must match for the filter to
         match.

   o  *conditions*: "(FilterCondition|FilterOperator)[]" The conditions
      to evaluate against each message.

   A *FilterCondition* object has the following properties, any of which
   may be omitted:

   o  *inMailbox*: "String" A mailbox id.  A message must be in this
      mailbox to match the condition.

   o  *inMailboxOtherThan*: "String" A mailbox id.  A message be in any
      mailbox other than this one to match the condition.  This is to
      allow messages solely in trash/spam to be easily excluded from a
      search.

   o  *before*: "Date" "UTCDate" The _receivedAt_ date of the message (as
      returned on the Message object) must be before this date to match
      the condition.

   o  *after*: "Date" "UTCDate" The _receivedAt_ date of the message (as
      returned on the Message object) must be on or after this date to
      match the condition.

   o  *minSize*: "Number" The size of the message in bytes (as returned
      on the Message object) must be equal to or greater than this
      number to match the condition.

   o  *maxSize*: "Number" The size of the message in bytes (as returned
      on the Message object) must be less than this number to match the
      condition.

   o  *allInThreadHaveKeyword*: "String" All messages (including this
      one) in the same thread as this message must have the given
      keyword to match the condition.

   o  *someInThreadHaveKeyword*: "String" At least one message (possibly
      this one) in the same thread as this message must have the given
      keyword to match the condition.

   o  *noneInThreadHaveKeyword*: "String" All messages (including this
      one) in the same thread as this message must *not* have the given
      keyword to match the condition.

   o  *hasKeyword*: "String" This message must have the given keyword to
      match the condition.

   o  *notKeyword*: "String" This message must not have the given
      keyword to match the condition.

   o  *hasAttachment*: "Boolean" The "hasAttachment" property of the
      message must be identical to the value given to match the
      condition.

   o  *text*: "String" Looks for the text in messages.  The server
      SHOULD look up text in the _from_, _to_, _cc_, _bcc_, _subject_,
      _textBody_, _htmlBody_ or _attachments_ properties of the message.
      The server MAY extend the search to any additional textual
      property.

   o  *from*: "String" Looks for the text in the _from_ property of the
      message.

   o  *to*: "String" Looks for the text in the _to_ property of the
      message.

   o  *cc*: "String" Looks for the text in the _cc_ property of the
      message.

   o  *bcc*: "String" Looks for the text in the _bcc_ property of the
      message.

   o  *subject*: "String" Looks for the text in the _subject_ property
      of the message.

   o  *body*: "String" Looks for the text in the _textBody_ or
      _htmlBody_ property of the message.

   o  *attachments*: "String" Looks for the text in the attachments of
      the message.  Server MAY handle text extraction when possible for
      the different kinds of media.

   o  *header*: "String[]" The array MUST contain either one or two
      elements.  The first element is the name of the header to match
      against.  The second (optional) element is the text to look for in
      the header.  If not supplied, the message matches simply if it
      _has_ a header of the given name.

   If zero properties are specified on the FilterCondition, the
   condition MUST always evaluate to "true".  If multiple properties are
   specified, ALL must apply for the condition to be "true" (it is
   equivalent to splitting the object into one-property conditions and
   making them all the child of an AND filter operator).

   The exact semantics for matching "String" fields is *deliberately not
   defined* to allow for flexibility in indexing implementation, subject
   to the following:

   o  Text SHOULD be matched in a case-insensitive manner.

   o  Text contained in either (but matched) single or double quotes
      SHOULD be treated as a *phrase search*, that is a match is
      required for that exact word or sequence of words, excluding the
      surrounding quotation marks.  Use "\"", "\'" and "\\" to match a
      literal """, "'" and "\" respectively in a phrase.

   o  Outside of a phrase, white-space SHOULD be treated as dividing
      separate tokens that may be searched for separately in the
      message, but MUST all be present for the message to match the
      filter.

   o  Tokens MAY be matched on a whole-word basis using stemming (so for
      example a text search for "bus" would match "buses" but not
      "business").

   o  When searching inside the _htmlBody_ property, HTML tags and
      attributes SHOULD be ignored.

4.3.2.  Sorting

   The following properties MUST be supported for sorting:

   o  *date*  *receivedAt* - The _receivedAt_ date as returned in the Message
      object.

   The following properties SHOULD be supported for sorting:

   o  *size* - The size as returned in the Message object.

   o  *from* - This is taken to be either the "name" part of the Emailer
      object, or if none then the "email" part of the Emailer object
      (see the definition of the from property in the Message object).
      If still none, consider the value to be the empty string.

   o  *to* - This is taken to be either the "name" part of the *first*
      Emailer object, or if none then the "email" part of the *first*
      Emailer object (see the definition of the to property in the
      Message object).  If still none, consider the value to be the
      empty string.

   o  *subject* - This is taken to be the subject of the Message with
      any ignoring any leading "Fwd:"s or "Re:"s (case-insensitive
      match).

   o  *keyword:*"$keyword"  *sentAt* - The _sentAt_ property on the Message object.

   o  *hasKeyword:*"keyword" - This value MUST be considered "true" if
      the message has the keyword, or "false" otherwise.

   o  *allThreadKeyword:*"$keyword"  *allInThreadHaveKeyword:*"keyword" - This value MUST be considered
      "true" for the message if *all* of the messages in the same thread
      (regardless of mailbox) have the keyword.

   o  *someThreadKeyword:*"$keyword"  *someInThreadHaveKeyword:*"keyword" - This value MUST be
      considered "true" for the message if *any* of the messages in the
      same thread (regardless of mailbox) have the keyword.

   The server MAY support sorting based on other properties as well.  A
   client can discover which properties are supported by inspecting the
   server's _capabilities_ object (see section 1).

   Example sort:

      `[ "someThreadKeyword:$Flagged "someInThreadHaveKeyword:$Flagged desc", "date "receivedAt desc" ]

   This would sort messages in flagged threads first (the thread is
   considered flagged if any message within it is flagged), and then in
   date order, newest first.  If two messages have both identical
   flagged status and date, the order is server-dependent but must be
   stable.

4.3.3.  Thread collapsing

   When "collapseThreads == true", then after filtering and sorting the
   message list, the list is further winnowed by removing any messages
   for a thread id that has already been seen (when passing through the
   list sequentially).  A thread will therefore only appear *once* in
   the "threadIds" list of the result, at the position of the first
   message in the list that belongs to the thread.

4.3.4.  Response

   The _messageList_ response has the following additional argument:

   o  *collapseThreads*: "Boolean" The _collapseThreads_ value that was
      used when calculating the message list for this call.

4.4.  getMessageListUpdates

   Standard _getFooListUpdates_ method, with the following additional
   arguments:

   o  *collapseThreads*: "Boolean" (default: "false") The
      _collapseThreads_ argument that was used with _getMessageList_.

   The _messageListUpdates_ response has the following additional
   arguments:

   o  *collapseThreads*: "Boolean" The _collapseThreads_ value that was
      used when calculating the message list for this call.

4.5.  setMessages

   Standard _setFoos_ method.  The _setMessages_ method encompasses:

   o  Creating a draft message

   o  Changing the flags of a message (unread/flagged status)

   o  Adding/removing a message to/from mailboxes (moving a message)

   o  Deleting messages
   When creating a message, the _headers_ property specifies extra
   headers to add in addition to any based off the parsed properties
   (like _from_/_to_/_subject_).  The keys MUST only contain the
   characters a-z (lower-case only), 0-9 and hyphens.  If a header is
   included that conflicts with one of the other properties on the
   Message object (e.g. _from_, _date_), the value in the _headers_
   object MUST be ignored.

   The server MAY also choose to set additional headers.  If not
   included, the server MUST generate and set a "Message-Id" header in
   conformance with [RFC5322] section 3.6.4.

   Other than making sure it conforms to the correct type, the server
   MUST NOT attempt to validate _from_/_to_/_cc_/_bcc_ (e.g. checking if
   an email address is valid) when creating a message.  This is to
   ensure draft messages can be saved at any point.

   Destroying a message removes it from all mailboxes to which it
   belonged.  To just delete a message to trash, simply change the
   "mailboxIds" property so it is now in the mailbox with "role ==
   "trash"", and remove all other mailbox ids.

   When emptying the trash, clients SHOULD NOT destroy messages which
   are also in a mailbox other than trash.  For those messages, they
   SHOULD just remove the Trash mailbox from the message.

   The following extra _SetError_ types are defined:

   For *create*:

   o  "attachmentNotFound": At least one blob id given in an attachment
      doesn't exist.  An extra _notFound_ property of type "String[]"
      MUST be included in the error object containing every _blobId_
      referenced in _attachments_ that could not be found on the server.

   o  "maxQuotaReached": The user has reached a server-defined limit on
      their message storage quota.

   For *update*:

   o  "tooManyKeywords": The change to the message's keywords would
      exceed a server-defined maximum.

4.6.  importMessages

   The _importMessages_ method adds [RFC5322] messages to a user's set
   of messages.  The messages must first be uploaded as a file using the
   standard upload mechanism.  It takes the following arguments:

   o  *accountId*: "String|null" The id of the account to use for this
      call.  If "null", defaults to the primary account.

   o  *messages*: "String[MessageImport]" A map of creation id (client
      specified) to MessageImport objects

   A *MessageImport* object has the following properties:

   o  *blobId*: "String" The id representing the raw [RFC5322] message
      (see the file upload section).

   o  *mailboxIds* "String[Boolean]" The ids of the mailbox(es) to
      assign this message to.  At least one mailbox MUST be given.

   o  *keywords*: "String[Boolean]" (default: "{}") The keywords to
      apply to the message.

   o  *receivedAt*: "UTCDate" (default: time of import on server) The
      _receivedAt_ date to set on the message.

   Each message to import is considered an atomic unit which may succeed
   or fail individually.  Importing successfully creates a new message
   object from the data reference by the blobId and applies the given
   mailboxes
   mailboxes, keywords and keywords. receivedAt date.

   The server MAY forbid two messages with the same exact [RFC5322]
   content, or even just with the same [RFC5322] Message-Id, to coexist
   within an account.  In this case, it should reject attempts to import
   a message considered a duplicate with an "alreadyExists" SetError.  A
   _messageId_ property of type "String" MUST be included on the error
   object with the id of the existing message.

   If the _blobId_, _mailboxIds_, or _keywords_ properties are invalid
   (e.g. missing, wrong type, id not found), the server MUST reject the
   import with an "invalidProperties" SetError.

   If the message cannot be imported because it would take the account
   over quota, the import should be rejected with a "maxQuotaReached"
   SetError.

   If the blob referenced cannot be parsed as an [RFC5322] message, the
   server MUST reject the import with an "invalidMessage" SetError.

   The response to _importMessages_ is called _messagesImported_. It has
   the following arguments:

   o  *accountId*: "String" The id of the account used for this call.

   o  *created*: "String[Message]" A map of the creation id to an object
      containing the _id_, _blobId_, _threadId_ and _size_ properties
      for each successfully imported Message.

   o  *notCreated*: "String[SetError]" A map of creation id to a
      SetError object for each Message that failed to be created.  The
      possible errors are defined above.

   The following errors may be returned instead of the _messageImported_
   response:

   "accountNotFound": Returned if an _accountId_ was explicitly included
   with the request, but it does not correspond to a valid account.

   "accountNotSupportedByMethod": Returned if the _accountId_ given
   corresponds to a valid account, but the account does not support this
   data type.

   "accountReadOnly": Returned if the account has "isReadOnly == true".

   "invalidArguments": Returned if one of the arguments is of the wrong
   type, or otherwise invalid.  A "description" property MAY be present
   on the response object to help debug with an explanation of what the
   problem was.

4.7.  copyMessages

   The only way to move messages *between* two different accounts is to
   copy them using the _copyMessages_ method, then once the copy has
   succeeded, delete the original.  It takes the following arguments:

   o  *fromAccountId*: "String|null" The id of the account to copy
      messages from.  If "null", defaults to the primary account.

   o  *toAccountId*: "String|null" The id of the account to copy
      messages to.  If "null", defaults to the primary account.

   o  *messages*: "String[MessageCopy]" A map of _creation id_ to a
      MessageCopy object.

   A *MessageCopy* object has the following properties:

   o  *messageId*: "String" The id of the message to be copied in the
      "from" account.

   o  *mailboxIds*: "String[Boolean]" The ids of the mailboxes (in the
      "to" account) to add the copied message to.  At least one mailbox
      MUST be given.

   o  *keywords*: "String[Boolean]" (default: "{}") The _keywords_
      property for the copy.

   o  *receivedAt*: "UTCDate" (default: _receivedAt_ date of original)
      The _receivedAt_ date to set on the copy.

   The server MAY forbid two messages with the same exact [RFC5322]
   content, or even just with the same [RFC5322] Message-Id, to coexist
   within an account.  If duplicates are allowed though, the "from"
   account may be the same as the "to" account to copy messages within
   an account.

   Each message copy is considered an atomic unit which may succeed or
   fail individually.  Copying successfully MUST create a new message
   object, with separate ids and mutable properties (e.g. mailboxes and
   keywords) to the original message.

   The response to _copyMessages_ is called _messagesCopied_. It has the
   following arguments:

   o  *fromAccountId*: "String" The id of the account messages were
      copied from.

   o  *toAccountId*: "String" The id of the account messages were copied
      to.

   o  *created*: "String[Message]|null" A map of the creation id to an
      object containing the _id_, _blobId_, _threadId_ and _size_
      properties for each successfully copied Message.

   o  *notCreated*: "String[SetError]|null" A map of creation id to a
      SetError object for each Message that failed to be copied, "null"
      if none.

   The *SetError* may be one of the following types:

   "alreadyExists": Returned if the server forbids duplicates and the
   message already exists in the target account.  A _messageId_ property
   of type "String" MUST be included on the error object with the id of
   the existing message.

   "notFound": Returned if the _messageId_ given can't be found.

   "invalidProperties": Returned if the _mailboxIds_ or _keywords_
   properties are invalid (e.g. missing, wrong type, id not found).

   "maxQuotaReached": Returned if the user has reached their mail quota
   so the message cannot be copied.

   The following errors may be returned instead of the _messagesCopied_
   response:

   "fromAccountNotFound": Returned if a _fromAccountId_ was explicitly
   included with the request, but it does not correspond to a valid
   account.

   "toAccountNotFound": Returned if a _toAccountId_ was explicitly
   included with the request, but it does not correspond to a valid
   account.

   "fromAccountNoMail": Returned if the _fromAccountId_ given
   corresponds to a valid account, but does not contain any mail data.

   "toAccountNoMail": Returned if the _toAccountId_ given corresponds to
   a valid account, but does not contain any mail data.

   "accountReadOnly": Returned if the "to" account has "isReadOnly ==
   true".

   "invalidArguments": Returned if one of the arguments is of the wrong
   type, or otherwise invalid.  A "description" property MAY be present
   on the response object to help debug with an explanation of what the
   problem was.

5.  MessageSubmission

   The MessageSubmission object represents the submission of a message
   for delivery to one or more recipients.  A *MessageSubmission* object
   has the following properties:

   o  *id*: "String" (immutable; server-set) The id of the message
      submission.

   o  *identityId*: "String" (immutable) The id of the identity to
      associate with this submission.

   o  *messageId*: "String" (immutable) The id of the message to send.
      The message being sent does not have to be a draft, for example
      when "redirecting" an existing message to a different email
      address.

   o  *threadId*: "String" (immutable; server-set) The thread id of the
      message to send.  This is set by the server to the _threadId_
      property of the message referenced by the _messageId_.

   o  *envelope*: "Envelope|null" (immutable; default: "null")
      Information for use when sending via SMTP.  An *Envelope* object
      has the following properties:

      *  *mailFrom*: "Address" The email address to use as the return
         address in the SMTP submission, plus any parameters to pass
         with the MAIL FROM address.  The JMAP server MAY allow the
         email to be the empty string.  When a JMAP server performs a
         message submission, it MAY use the same id string for the
         [RFC3461] ENVID parameter and the MessageSubmission object id.
         Servers that do this MAY replace a client-provided value for
         ENVID with a server-provided value.

      *  *rcptTo*: "Address[]" The email addresses to send the message
         to, and any RCPT TO parameters to pass with the recipient.

      An *Address* object has the following properties:

      *  *email*: "String" The email address being represented by the
         object.  This as a "Mailbox" as used in the Reverse-path or
         Foward-path of the MAIL FROM or RCPT TO command in [@!RFC5321

      *  *parameters*: "Object|null" Any parameters to send with the
         email (either mail-parameter or rcpt-parameter as appropriate,
         as specified in [RFC5321]).  If supplied, each key in the
         object is a parameter name, and the value either the parameter
         value (type "String") or if the parameter does not take a value
         then "null".  For both name and value, any xtext or unitext
         encodings are removed ([RFC3461], [RFC6533]) and JSON string
         encoding applied.

      If the _envelope_ property is "null" or omitted on creation, the
      server MUST generate this from the referenced message as follows:

      *  *mailFrom*: The email in the _Sender_ header, if present,
         otherwise the _From_ header, if present, and no parameters.  If
         multiple addresses are present in one of these headers, or
         there is more than one _Sender_/_From_ header, the server
         SHOULD reject the message as invalid but otherwise MUST take
         the first email address in the last _Sender_/_From_ header in
         the [RFC5322] version of the message.  If the address found
         from this is not allowed by the identity associated with this
         submission, the _email_ property from the identity MUST be used
         instead.

      *  *rcptTo*: The deduplicated set of email addresses from the
         _To_, _Cc_ and _Bcc_ headers, if present, with no parameters
         for any of them.

   o  *sendAt*: "Date" "UTCDate" (immutable; server-set) The date the message was/
      will
      was/will be released for delivery.  If the client successfully
      used [RFC4865] FUTURERELEASE with the message, this MUST be the
      time when the server will release the message; otherwise it MUST
      be the time the MessageSubmission was created.

   o  *undoStatus*: "String" (server-set) This represents whether the
      submission may be canceled.  This is server set and MUST be one of
      the following values:

      *  "pending": It MAY be possible to cancel this submission.

      *  "final": The message has been relayed to at least one recipient
         in a manner that cannot be recalled.  It is no longer possible
         to cancel this submission.

      *  "canceled": The message submission was canceled and will not be
         delivered to any recipient.

      On systems that do not support unsending, the value of this
      property will always be "final".  On systems that do support
      canceling submission, it will start as "pending", and MAY
      transition to "final" when the server knows it definitely cannot
      recall the message, but MAY just remain "pending".  If in pending
      state, a client can attempt to cancel the submission by setting
      this property to "canceled"; if the update succeeds, the
      submission was successfully canceled and the message has not been
      delivered to any of the original recipients.

   o  *deliveryStatus*: "String[DeliveryStatus]|null" (server-set) This
      represents the delivery status for each of the message recipients,
      if known.  This property MAY not be supported by all servers, in
      which case it will remain "null".  Servers that support it SHOULD
      update the MessageSubmission object each time the status of any of
      the recipients changes, even if some recipients are still being
      retried.  This value is a map from the email address of each
      recipient to a _DeliveryStatus_ object.  A *DeliveryStatus* object
      has the following properties:

      *  *smtpReply*: "String" The SMTP reply string returned for this
         recipient when the server last tried to relay the message, or
         in a later DSN response for the message.  This SHOULD be the
         response to the RCPT TO stage, unless this was accepted and the
         message as a whole rejected at the end of the DATA stage, in
         which case the DATA stage reply SHOULD be used instead.  Multi-
         line SMTP responses should be concatenated to a single string
         as follows:

         +  The hyphen following the SMTP code on all but the last line
            is replaced with a space.

         +  Any prefix in common with the first line is stripped from
            lines after the first.

         +  CRLF is replaced by a space.

         For example:

          550-5.7.1 Our system has detected that this message is
          550 5.7.1 likely spam, sorry.

         would become:

550 5.7.1 Our system has detected that this message is likely spam, sorry.

         For messages relayed via an alternative to SMTP, the server MAY
         generate a synthetic string representing the status instead.
         If it does this, the string MUST be of the following form:

         +  A 3-digit SMTP reply code, as defined in [RFC5321], section
            4.2.3.

         +  Then a single space character.

         +  Then an SMTP Enhanced Mail System Status Code as defined in
            [RFC3463], with a registry defined in [RFC5248].

         +  Then a single space character.

         +  Then an implementation-specific information string with a
            human readable explanation of the response.

      *  *delivered*: "String" Represents whether the message has been
         successfully delivered to the recipient.  This MUST be one of
         the following values:

         +  "queued": The message is in a local mail queue and status
            will change once it exits the local mail queues.  The
            _smtpReply_ property may still change.

         +  "yes": The message was successfully delivered to the mailbox
            of the recipient.  The _smtpReply_ property is final.

         +  "no": Message delivery to the recipient permanently failed.
            The _smtpReply_ property is final.

         +  "unknown": The final delivery status is unknown, (e.g. it
            was relayed to an external machine and no further
            information is available).  The _smtpReply_ property may
            still change if a DSN arrives.

         Note, successful relaying to an external SMTP server SHOULD NOT
         be taken as an indication that the message has successfully
         reached the final mailbox.  In this case though, the server MAY
         receive a DSN response, if requested.  If a DSN is received for
         the recipient with Action equal to "delivered", as per
         [RFC3464] section 2.3.3, then the _delivered_ property SHOULD
         be set to "yes"; if the Action equals "failed", the property
         SHOULD be set to "no".  Receipt of any other DSN SHOULD NOT
         affect this property.  The server MAY also set this property
         based on other feedback channels.

      *  *displayed*: "String" Represents whether the message has been
         displayed to the recipient.  This MUST be one of the following
         values:

         +  "unknown": The display status is unknown.  This is the
            initial value.

         +  "yes": The receipient's recipient's system claims the message content has
            been displayed to the recipient.  Note, there is no
            guarantee that the recipient has noticed, read, or
            understood the content.

         If an MDN is received for this recipient with Disposition-Type
         (as per [RFC3798] section 3.2.6.2) equal to "displayed", this
         property SHOULD be set to "yes".  The server MAY also set this
         property based on other feedback channels.

   o  *dsnBlobIds*: "String[]" (server-set) A list of blob ids for DSNs
      received for this submission, in order of receipt, oldest first.

   o  *mdnBlobIds*: "String[]" (server-set) A list of blob ids for MDNs
      received for this submission, in order of receipt, oldest first.

   JMAP servers MAY choose not to expose DSN and MDN responses as
   Message objects if they correlate to a MessageSubmission object.  It
   SHOULD only do this if it exposes them in the _dsnBlobIds_ and
   _mdnblobIds_ fields instead, and expects the user to be using clients
   capable of fetching and displaying delivery status via the
   MessageSubmission object.

   For efficiency, a server MAY destroy MessageSubmission objects a
   certain amount of time after the message is successfully sent or it
   has finished retrying sending the message.  For very basic SMTP
   proxies, this MAY be immediately after creation, as it has no way to
   assign a real id and return the information again if fetched later.

   The following JMAP methods are supported:

5.1.  getMessageSubmissions

   Standard _getFoos_ method.

5.2.  getMessageSubmissionUpdates

   Standard _getFooUpdates_ method.

5.3.  getMessageSubmissionList

   Standard _getFooList_ method.

   The *FilterCondition* object (optionally passed as the _filter_
   argument) has the following properties, any of which may be omitted:

   o  *messageIds*: "String[]" The MessageSubmission _messageId_
      property must be in this list to match the condition.

   o  *threadIds*: "String[]" The MessageSubmission _threadId_ property
      must be in this list to match the condition.

   o  *undoStatus*: "String" The MessageSubmission _undoStatus_ property
      must be identical to the value given to match the condition.

   o  *before*: "Date" "UTCDate" The _sendAt_ property of the MessageSubmission
      object must be before this date to match the condition.

   o  *after*: "Date" "UTCDate" The _sendAt_ property of the MessageSubmission
      object must be after this date to match the condition.

   A MessageSubmission object matches the filter if and only if all of
   the given conditions given match.  If zero properties are specified,
   it is automatically "true" for all objects.

   The following properties MUST be supported for sorting:

   o  "messageId"

   o  "threadId"

   o  "sentAt"

5.4.  getMessageSubmissionListUpdates

   Standard _getFooListUpdates_ method.

5.5.  setMessageSubmissions

   Standard _setFoos_ method, with the following two extra arguments:

   o  *onSuccessUpdateMessage*: "String[Message]|null" A map of
      _MessageSubmission id_ to an object containing properties to
      update on the Message object referenced by the MessageSubmission
      if the create/update/destroy succeeds.  (For references to
      MessageSubmission creations, this is equivalent to a back
      reference so the id will be the creation id prefixed with a "#".)

   o  *onSuccessDestroyMessage*: "String[]|null" A list of
      _MessageSubmission ids_ for which the message with the
      corresponding messageId should be destroyed if the create/update/
      destroy succeeds.  (For references to MessageSubmission creations,
      this is equivalent to a back reference so the id will be the
      creation id prefixed with a "#".)

   A single implicit _setMessages_ call MUST be made after all
   MessageSubmission create/update/destroy requests have been processed
   to perform any changes requested in these two arguments.  The
   _messagesSet_ response MUST be returned after the
   _messageSubmissionsSet_ response.

   A message is sent by creating a MessageSubmission object.  When
   processing each create, the server must check that the message is
   valid, and the user has sufficient authorization to send it.  If the
   creation succeeds, the message will be sent to the recipients given
   in the envelope _rcptTo_ parameter.  The server MUST remove any _Bcc_
   header present on the message during delivery.  The server MAY add or
   remove other headers from the submitted message, or make further
   alterations in accordance with the server's policy during delivery.

   If the referenced message is destroyed at any point after the
   MessageSubmission object is created, this MUST NOT change the
   behaviour of the message submission (i.e. it does not cancel a future
   send).

   Similarly, destroying a MessageSubmission object MUST NOT affect the
   deliveries it represents.  It purely removes the record of the
   message submission.  The server MAY automatically destroy
   MessageSubmission objects after a certain time or in response to
   other triggers, and MAY forbid the client from manually destroying
   MessageSubmission objects.

   The following extra _SetError_ types are defined:

   For *create*:

   o  "tooLarge" - The message size is larger than the server supports.
      A _maxSize_ "Number" property MUST be present on the SetError
      specifying the maximum size of a message that may be sent, in
      bytes.

   o  "tooManyRecipients" - The envelope (supplied or generated) has
      more recipients than the server allows.  A _maxRecipients_
      "Number" property MUST be present on the SetError specifying the
      maximum number of allowed recipients.

   o  "noRecipients" - The envelope (supplied or generated) does not
      have any rcptTo emails.

   o  "invalidRecipients" - The _rcptTo_ property of the envelope
      (supplied or generated) contains at least one rcptTo value which
      is not a valid email for sending to.  An _invalidEmails_
      "String[]" property MUST be present on the SetError, which is a
      list of the invalid emails.

   o  "notPermittedFrom" - The server does not permit the user to send a
      message with the From header of the message to be sent.

   o  "notPermittedToSend" - The user does not have permission to send
      at all right now for some reason.  A _description_ "String"
      property MAY be present on the SetError object to display to the
      user why they are not permitted.

   o  "messageNotFound" - The _messageId_ is not a valid id for a
      message in the account.

   o  "invalidMessage" - The message to be sent is invalid in some way.
      The SetError SHOULD contain a property called _properties_ of type
      "String[]" that lists *all* the properties of the Message that
      were invalid.

   For *update*:

   o  "cannotUnsend": The client attempted to update the _undoStatus_ of
      a valid MessageSubmission object from "pending" to "canceled", but
      the message cannot be unsent.

   For *destroy*:

   o  "forbidden": The server does not allow clients to destroy
      MessageSubmission objects.

6.  Identities

   An *Identity* object stores information about an email address (or
   domain) the user may send from.  It has the following properties:

   o  *id*: "String" (immutable; server-set) The id of the identity.

   o  *name*: "String" (default: """") The "From" _name_ the client
      SHOULD use when creating a new message from this identity.

   o  *email*: "String" The "From" email address the client MUST use
      when creating a new message from this identity.  This property is
      immutable.  The "email" property MAY alternatively be of the form
      "*@example.com", in which case the client may use any valid email
      address ending in "@example.com".

   o  *replyTo*: "Emailer[]|null" (default: "null") The Reply-To value
      the client SHOULD set when creating a new message from this
      identity.

   o  *bcc*: "Emailer[]|null" (default: "null") The Bcc value the client
      SHOULD set when creating a new message from this identity.

   o  *textSignature*: "String" (default: """") Signature the client
      SHOULD insert into new rich-text plain-text messages that will be sending sent from
      this identity.  Clients MAY ignore this and/or combine this with a
      client-specific signature preference.

   o  *htmlSignature*: "String" (default: """") Signature the client
      SHOULD insert into new HTML messages that will be sending sent from this
      identity.  This text MUST be an HTML snippet to be inserted into
      the "<body></body>" section of the new email.  Clients MAY ignore
      this and/or combine this with a client-specific signature
      preference.

   o  *mayDelete*: "Boolean" (server-set) Is the user allowed to delete
      this identity?  Servers may wish to set this to "false" for the
      user's username or other default address.

   Multiple identities with the same email address MAY exist, to allow
   for different settings the user wants to pick between (for example
   with different names/signatures).

   The following JMAP methods are supported:

6.1.  getIdentities

   Standard _getFoos_ method.  The _ids_ argument may be "null" to fetch
   all at once.

6.2.  getIdentityUpdates

   Standard _getFooUpdates_ method.

6.3.  setIdentities

   Standard _setFoos_ method.  The following extra _SetError_ types are
   defined:

   For *create*:

   o  "maxQuotaReached": The user has reached a server-defined limit on
      the number of identities.

   o  "emailNotPermitted": The user is not alloed allowed to send from the
      address given as the _email_ property of the identity.

   For *destroy*:

   o  "forbidden": Returned if the identity's _mayDelete_ value is
      "false".

7.  SearchSnippets

   When doing a search on a "String" property, the client may wish to
   show the relevant section of the body that matches the search as a
   preview instead of the beginning of the message, and to highlight any
   matching terms in both this and the subject of the message.  Search
   snippets represent this data.

   A *SearchSnippet* object has the following properties:

   o  *messageId*: "String" The message id the snippet applies to.

   o  *subject*: "String|null" If text from the filter matches the
      subject, this is the subject of the message HTML-escaped, with
      matching words/phrases wrapped in "<mark></mark>" tags.  If it
      does not match, this is "null".

   o  *preview*: "String|null" If text from the filter matches the
      plain-text or HTML body, this is the relevant section of the body
      (converted to plain text if originally HTML), HTML-escaped, with
      matching words/phrases wrapped in "<mark></mark>" tags, up to 256
      characters long.  If it does not match, this is "null".

   o  *attachments*: "String|null" If text from the filter matches the
      text extracted from an attachment, this is the relevant section of
      the attachment (converted to plain text), with matching words/
      phrases wrapped in "<mark></mark>" tags, up to 256 characters
      long.  If it does not match, this is "null".

   It is server-defined what is a relevant section of the body for
   preview.  If the server is unable to determine search snippets, it
   MUST return "null" for both the _subject_, _preview_ and
   _attachments_ properties.

   Note, unlike most data types, a SearchSnippet DOES NOT have a
   property called "id".

   The following JMAP method is supported:

7.1.  getSearchSnippets

   To fetch search snippets, make a call to "getSearchSnippets".  It
   takes the following arguments:

   o  *accountId*: "String|null" The id of the account to use for this
      call.  If "null", defaults to the primary account.

   o  *messageIds*: "String[]" The list of ids of messages to fetch the
      snippets for.

   o  *filter*: "FilterCondition|FilterOperator|null" The same filter as
      passed to getMessageList; see the description of this method for
      details.

   The response to "getSearchSnippets" is called "searchSnippets".  It
   has the following arguments:

   o  *accountId*: "String" The id of the account used for the call.

   o  *filter*: "FilterCondition|FilterOperator|null" Echoed back from
      the call.

   o  *list*: "SearchSnippet[]" An array of SearchSnippet objects for
      the requested message ids.  This may not be in the same order as
      the ids that were in the request.

   o  *notFound*: "String[]|null" An array of message ids requested
      which could not be found, or "null" if all ids were found.

   Since snippets are only based on immutable properties, there is no
   state string or update mechanism needed.

   The following errors may be returned instead of the _searchSnippets_
   response:

   "accountNotFound": Returned if an _accountId_ was explicitly included
   with the request, but it does not correspond to a valid account.

   "accountNotSupportedByMethod": Returned if the _accountId_ given
   corresponds to a valid account, but the account does not support this
   data type.

   "requestTooLarge": Returned if the number of _messageIds_ requested
   by the client exceeds the maximum number the server is willing to
   process in a single method call.

   "cannotDoFilter": Returned if the server is unable to process the
   given _filter_ for any reason.

   "invalidArguments": Returned if the request does not include one of
   the required arguments, or one of the arguments is of the wrong type,
   or otherwise invalid.  A "description" property MAY be present on the
   response object to help debug with an explanation of what the problem
   was.

8.  Vacation Response

   The *VacationResponse* object represents the state of vacation-
   response related settings for an account.  It has the following
   properties:

   o  *id*: "String" (immutable) The id of the object.  There is only
      ever one vacation response object, and its id is ""singleton"".

   o  *isEnabled* "Boolean" Should a vacation response be sent if a
      message arrives between the _fromDate_ and _toDate_?

   o  *fromDate*: "Date|null" "UTCDate|null" If _isEnabled_ is "true", the date/time
      after which messages that arrive should receive the user's
      vacation response, in UTC.  If "null", the vacation response is
      effective immediately.

   o  *toDate*: "Date|null" "UTCDate|null" If _isEnabled_ is "true", the date/time
      after which messages that arrive should no longer receive the
      user's vacation response, in UTC.  If "null", the vacation
      response is effective indefinitely.

   o  *subject*: "String|null" The subject that will be used by the mail
      sent in response to messages when the vacation response is
      enabled.  If null, an appropriate subject SHOULD be set by the
      server.

   o  *textBody*: "String|null" The plain text part of the message to
      send in response to messages when the vacation response is
      enabled.  If this is "null", when the vacation message is sent a
      plain-text body part SHOULD be generated from the _htmlBody_ but
      the server MAY choose to send the response as HTML only.

   o  *htmlBody*: "String|null" The HTML message to send in response to
      messages when the vacation response is enabled.  If this is
      "null", when the vacation message is sent an HTML body part MAY be
      generated from the _textBody_, or the server MAY choose to send
      the response as plain-text only.

   The following JMAP methods are supported:

8.1.  getVacationResponse

   Standard _getFoos_ method.

   There MUST only be exactly one VacationResponse object in an account.
   It MUST have the id ""singleton"".

8.2.  setVacationResponse

   Standard _setFoos_ method.  The following extra _SetError_ types are
   defined:

   For *create* or *destroy*:

   o  "singleton": This is a singleton object, so you cannot create
      another one or destroy the existing one.

9.  Security considerations

   All security considerations of JMAP {TODO: insert RFC ref} apply to
   this specification.

10.  References

10.1.  Normative References

   [RFC1870]  Klensin, J., Freed, N., and K. Moore, "SMTP Service
              Extension for Message Size Declaration", STD 10, RFC 1870,
              DOI 10.17487/RFC1870, November 1995,
              <https://www.rfc-editor.org/info/rfc1870>.

   [RFC2047]  Moore, K., "MIME (Multipurpose Internet Mail Extensions)
              Part Three: Message Header Extensions for Non-ASCII Text",
              RFC 2047, DOI 10.17487/RFC2047, November 1996,
              <https://www.rfc-editor.org/info/rfc2047>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2852]  Newman, D., "Deliver By SMTP Service Extension", RFC 2852,
              DOI 10.17487/RFC2852, June 2000,
              <https://www.rfc-editor.org/info/rfc2852>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

   [RFC3461]  Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
              Extension for Delivery Status Notifications (DSNs)",
              RFC 3461, DOI 10.17487/RFC3461, January 2003,
              <https://www.rfc-editor.org/info/rfc3461>.

   [RFC3463]  Vaudreuil, G., "Enhanced Mail System Status Codes",
              RFC 3463, DOI 10.17487/RFC3463, January 2003,
              <https://www.rfc-editor.org/info/rfc3463>.

   [RFC3464]  Moore, K. and G. Vaudreuil, "An Extensible Message Format
              for Delivery Status Notifications", RFC 3464,
              DOI 10.17487/RFC3464, January 2003,
              <https://www.rfc-editor.org/info/rfc3464>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.

   [RFC3798]  Hansen, T., Ed. and G. Vaudreuil, Ed., "Message
              Disposition Notification", RFC 3798, DOI 10.17487/RFC3798,
              May 2004, <https://www.rfc-editor.org/info/rfc3798>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/info/rfc4648>.

   [RFC4865]  White, G. and G. Vaudreuil, "SMTP Submission Service
              Extension for Future Message Release", RFC 4865,
              DOI 10.17487/RFC4865, May 2007,
              <https://www.rfc-editor.org/info/rfc4865>.

   [RFC5248]  Hansen, T. and J. Klensin, "A Registry for SMTP Enhanced
              Mail System Status Codes", BCP 138, RFC 5248,
              DOI 10.17487/RFC5248, June 2008,
              <https://www.rfc-editor.org/info/rfc5248>.

   [RFC5321]  Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
              DOI 10.17487/RFC5321, October 2008,
              <https://www.rfc-editor.org/info/rfc5321>.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <https://www.rfc-editor.org/info/rfc5322>.

   [RFC5788]  Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry",
              RFC 5788, DOI 10.17487/RFC5788, March 2010,
              <https://www.rfc-editor.org/info/rfc5788>.

   [RFC6409]  Gellens, R. and J. Klensin, "Message Submission for Mail",
              STD 72, RFC 6409, DOI 10.17487/RFC6409, November 2011,
              <https://www.rfc-editor.org/info/rfc6409>.

   [RFC6533]  Hansen, T., Ed., Newman, C., and A. Melnikov,
              "Internationalized Delivery Status and Disposition
              Notifications", RFC 6533, DOI 10.17487/RFC6533, February
              2012, <https://www.rfc-editor.org/info/rfc6533>.

   [RFC6710]  Melnikov, A. and K. Carlberg, "Simple Mail Transfer
              Protocol Extension for Message Transfer Priorities",
              RFC 6710, DOI 10.17487/RFC6710, August 2012,
              <https://www.rfc-editor.org/info/rfc6710>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [RFC7493]  Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
              DOI 10.17487/RFC7493, March 2015,
              <https://www.rfc-editor.org/info/rfc7493>.

10.2.  URIs

   [1] server.html

   [2] https://www.iana.org/assignments/imap-keywords/imap-
       keywords.xhtml

Author's Address

   Neil Jenkins
   FastMail
   Level 2, 114 William St
   Melbourne  VIC 3000
   Australia

   Email: neilj@fastmailteam.com
   URI:   https://www.fastmail.com