JMAP N. Jenkins
Internet-Draft FastMail
Updates: 5788 (if approved) C. Newman
Intended status: Standards Track Oracle
Expires: September 2, 2019 March 1, 2019

JMAP for Mail
draft-ietf-jmap-mail-15

Abstract

This document specifies a data model for synchronising email data with a server using JMAP. Clients can use this to efficiently search, access, organise and send messages, and get pushed notifications for fast resynchronisation when new messages are delivered or a change is made in another client.

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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on September 2, 2019.

Copyright Notice

Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

1. Introduction

JMAP ([I-D.ietf-jmap-core] – JSON Meta Application Protocol) 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 accessing a mail store over JMAP, allowing you to query, read, organise and submit mail for sending.

The data model is designed to allow a server to provide consistent access to the same data via IMAP ([RFC3501]) as well as JMAP. As in IMAP, a message must belong to a mailbox, however in JMAP its id does not change if you move it between mailboxes, and the server may allow it to belong to multiple mailboxes simultaneously (often exposed in a user agent as labels rather than folders).

As in IMAP, emails may also be assigned zero or more keywords: short arbitrary strings. These are primarily intended to store metadata to inform client display, such as unread status or whether a message has been replied to. An IANA registry allows common semantics to be shared between clients and extended easily in the future.

A message and its replies are linked on the server by a common thread id. Clients may fetch the list of messages with a particular thread id to more easily present a threaded or conversational interface.

Permissions for message access happen on a per-mailbox basis. Servers may give the user restricted permissions for certain mailboxes, for example if another user's inbox has been shared read-only with them.

1.1. Notational conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

Type signatures, examples and property descriptions in this document follow the conventions established in section 1.1 of [I-D.ietf-jmap-core]. Data types defined in the core specification are also used in this document.

Servers MUST support all properties specified for the new data types defined in this document.

1.2. Terminology

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

1.3. Additions to the capabilities object

The capabilities object is returned as part of the JMAP Session object; see [I-D.ietf-jmap-core], section 2.

This document defines three additional capability URIs.

1.3.1. urn:ietf:params:jmap:mail

This represents support for the Mailbox, Thread, Email, and SearchSnippet data types and associated API methods. The value of this property is an object which MUST contain the following information on server capabilities:

1.3.2. urn:ietf:params:jmap:submission

This represents support for the Identity and MessageSubmission data types and associated API methods. The value of this property is an object which MUST contain the following information on server capabilities:

1.3.3. urn:ietf:params:jmap:vacationresponse

This represents support for the VacationResponse data type and associated API methods. The value of this property is an empty object.

1.4. Data type support in different accounts

The server MUST include the appropriate capability strings in the hasDataFor property of any account with which the user may use the data types represented by that URI. Supported data types may differ between accounts the user has access to. For example, in the user's personal account they may have access to all three sets of data, but in a shared account they may only have data for urn:ietf:params:jmap:mail. This means they can access Mailbox/Thread/Email data in the shared account but are not allowed to send as that account (and so do not have access to Identity/MessageSubmission objects) or view/set its vacation response.

1.5. Push

Servers MUST support the JMAP push mechanisms, as specified in [I-D.ietf-jmap-core] section 7, to receive notifications when the state changes for any of the types defined in this specification.

In addition, servers MUST support pushing state changes for a type called "EmailDelivery". There are no methods to act on this type; it only exists as part of the push mechanism. The state string for this MUST change whenever a new Email is added to the store, but SHOULD NOT change upon any other change to the Email objects, for example if one is marked as read or deleted.

Clients in battery constrained environments may wish to delay fetching changes initiated by the user, but fetch new messages immediately so they can notify the user. To do this, they can register for pushes for the EmailDelivery type rather than the Email type (defined in section 4).

1.5.1. Example

The client has registered for push notifications (see [I-D.ietf-jmap-core]) just for the EmailDelivery type. The user marks an email as read on another device, causing the state string for the Email type to change, however as nothing new was added to the store the EmailDelivery state does not change and nothing is pushed to the client. A new message arrives in the user's inbox, again causing the Email state to change. This time the EmailDelivery state also changes, and a StateChange object is pushed to the client with the new state string. The client may then resync to fetch the new message immediately.

1.6. Ids

If a JMAP Mail server also provides an IMAP interface to the data and supports [RFC8474] IMAP Extension for Object Identifiers, the ids SHOULD be the same for mailbox, thread, and email objects in JMAP.

2. Mailboxes

A mailbox represents a named set of emails. This is the primary mechanism for organising emails 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, an email MUST belong to one or more mailboxes. The email id does not change if the email changes mailboxes.

A Mailbox object has the following properties:

For IMAP compatibility, an email 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. Mailbox/get

Standard "/get" method. The ids argument may be null to fetch all at once.

2.2. Mailbox/changes

Standard "/changes" method, but with one extra argument to the response:

Since counts frequently change but other properties are generally only changed rarely, the server can help the client optimise data transfer by keeping track of changes to email/thread counts separately to other state changes. The updatedProperties array may be used directly via a back-reference in a subsequent Mailbox/get call in the same single request so only these properties are returned if nothing else has changed.

2.3. Mailbox/query

Standard "/query" method, but with the following additional argument:

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

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

The following properties MUST be supported for sorting:

2.4. Mailbox/queryChanges

Standard "/queryChanges" method.

2.5. Mailbox/set

Standard "/set" method, but with the following additional argument:

The following extra SetError types are defined:

For destroy:

2.6. Example

Fetching all mailboxes in an account: 

[[ "Mailbox/get", {
  "accountId": "u33084183",
  "ids": null
}, "0" ]]

And response: 

[[ "Mailbox/get", {
  "accountId": "u33084183",
  "state": "78540",
  "list": [{
    "id": "MB23cfa8094c0f41e6",
    "name": "Inbox",
    "parentId": null,
    "role": "inbox",
    "sortOrder": 10,
    "totalEmails": 16307,
    "unreadEmails": 13905,
    "totalThreads": 5833,
    "unreadThreads": 5128,
    "myRights": {
      "mayAddItems": true,
      "mayRename": false,
      "maySubmit": true,
      "mayDelete": false,
      "maySetKeywords": true,
      "mayRemoveItems": true,
      "mayCreateChild": true,
      "maySetSeen": true,
      "mayReadItems": true
    },
    "isSubscribed": true
  }, {
    "id": "MB674cc24095db49ce",
    "name": "Important mail",
    ...
  }, ... ],
  "notFound": []
}, "0" ]]

Now suppose a message is marked read and we get a push update that the Mailbox state has changed. You might fetch the updates like this: 

[[ "Mailbox/changes", {
  "accountId": "u33084183",
  "sinceState": "78540"
}, "0" ],
[ "Mailbox/get", {
  "accountId": "u33084183",
  "#ids": {
    "resultOf": "0",
    "name": "Mailbox/changes",
    "path": "/created"
  }
}, "1" ],
[ "Mailbox/get", {
  "accountId": "u33084183",
  "#ids": {
    "resultOf": "0",
    "name": "Mailbox/changes",
    "path": "/updated"
  },
  "#properties": {
    "resultOf": "0",
    "name": "Mailbox/changes",
    "path": "/updatedProperties"
  }
}, "2" ]]

This fetches the list of ids for created/updated/destroyed mailboxes, then using back-references fetches the data for just the created/updated mailboxes in the same request. The response may look something like this: 

[[ "Mailbox/changes", {
  "accountId": "u33084183",
  "oldState": "78541",
  "newState": "78542",
  "hasMoreChanges": false,
  "updatedProperties": [
    "totalEmails", "unreadEmails",
    "totalThreads", "unreadThreads"
  ],
  "created": [],
  "updated": ["MB23cfa8094c0f41e6"],
  "destroyed": []
}, "0" ],
[ "Mailbox/get", {
  "accountId": "u33084183",
  "state": "78542",
  "list": [],
  "notFound": []
}, "1" ],
[ "Mailbox/get", {
  "accountId": "u33084183",
  "state": "78542",
  "list": [{
    "id": "MB23cfa8094c0f41e6",
    "totalEmails": 16307,
    "unreadEmails": 13903,
    "totalThreads": 5833,
    "unreadThreads": 5127
  }],
  "notFound": []
}, "2" ]]

Here's an example where we try to rename one mailbox and destroy another: 

[[ "Mailbox/set", {
  "accountId": "u33084183",
  "ifInState": "78542",
  "update": {
    "MB674cc24095db49ce": {
      "name": "Maybe important mail"
    }
  },
  "destroy": [ "MB23cfa8094c0f41e6" ]
}, "0" ]]

Suppose the rename succeeds, but we don't have permission to destroy the mailbox we tried to destroy, we might get back: 

[[ "Mailbox/set", {
  "accountId": "u33084183",
  "oldState": "78542",
  "newState": "78549",
  "updated": {
      "MB674cc24095db49ce": null
  },
  "notDestroyed": {
    "MB23cfa8094c0f41e6": {
      "type": "forbidden"
    }
  }
}, "0" ]]

3. Threads

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

The exact algorithm for determining whether two emails belong to the same thread is not mandated in this spec to allow for compatibility with different existing systems. For new implementations, it is suggested that two messages belong in the same thread if both of the following conditions apply:

  1. An identical RFC5322 message id appears in both messages in any of the Message-Id, In-Reply-To and References headers.
  2. After stripping automatically added prefixes such as "Fwd:", "Re:", "[List-Tag]" etc. and ignoring whitespace, the subjects are the same. This avoids the situation where a person replies to an old message as a convenient way of finding the right recipient to send to, but changes the subject and starts a new conversation.

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

A Thread object has the following properties:

The following JMAP methods are supported:

3.1. Thread/get

Standard "/get" method.

3.1.1. Example

Request: 

[[ "Thread/get", {
  "accountId": "acme",
  "ids": ["f123u4", "f41u44"]
}, "#1" ]]

with response: 

[[ "Thread/get", {
  "accountId": "acme",
  "state": "f6a7e214",
  "list": [
    {
      "id": "f123u4",
      "emailIds": [ "eaa623", "f782cbb"]
    },
    {
      "id": "f41u44",
      "emailIds": [ "82cf7bb" ]
    }
  ],
  "notFound": []
}, "#1" ]]

3.2. Thread/changes

Standard "/changes" method.

4. Emails

The Email object is a representation of an [RFC5322] message, which allows clients to avoid the complexities of MIME parsing, transfer encoding and character encoding.

4.1. Properties of the Email object

Broadly, a message consists of two parts: a list of header fields, then a body. The JMAP Email object provides a way to access the full structure, or to use simplified properties and avoid some complexity if this is sufficient for the client application.

While raw headers can be fetched and set, the vast majority of clients should use an appropriate parsed form for each of the headers it wants to process, as this allows it to avoid the complexities of various encodings that are required in a valid RFC5322 message.

The body of a message is normally a MIME-encoded set of documents in a tree structure. This may be arbitrarily nested, but the majority of email clients present a flat model of an email body (normally plain text or HTML), with a set of attachments. Flattening the MIME structure to form this model can be difficult, and causes inconsistency between clients. Therefore in addition to the bodyStructure property, which gives the full tree, the Email object contains 3 alternate properties with flat lists of body parts:

Because MIME allows for multiple representations of the same data (using multipart/alternative), there is a textBody property (which prefers a plain text representation) and an htmlBody property (which prefers an HTML representation) to accommodate the two most common client requirements. The same part may appear in both lists where there is no alternative between the two.

The bodyValues property allows for clients to fetch the value of text parts directly without having to do a second request for the blob, and have the server handle decoding the charset into unicode. This data is in a separate property rather than on the EmailBodyPart object to avoid duplication of large amounts of data, as the same part may be included twice if the client fetches more than one of bodyStructure, textBody and htmlBody.

Due to the number of properties involved, the set of Email properties is specified over the following three sub-sections.

4.1.1. Metadata

These properties represent metadata about the [RFC5322] message, and are not derived from parsing the message itself.

4.1.2. Header fields parsed forms

Header field properties are derived from the [RFC5322] and [RFC6532] message header fields. All header fields may be fetched in a raw form. Some headers may also be fetched in a parsed form. The structured form that may be fetched depends on the header. The following forms are defined:

4.1.2.1. Raw

Type: String

The raw octets of the header field value from the first octet following the header field name terminating colon, up to but excluding the header field terminating CRLF. Any standards-compliant message MUST be either ASCII (RFC5322) or UTF-8 (RFC6532), however other encodings exist in the wild. A server SHOULD replace any octet or octet run with the high bit set that violates UTF-8 syntax with the unicode replacement character (U+FFFD). Any NUL octet MUST be dropped.

This form will typically have a leading space, as most generated messages insert a space after the colon that terminates the header field name.

4.1.2.2. Text

Type: String

The header field value with:

  1. White space unfolded (as defined in [RFC5322] section 2.2.3).
  2. The terminating CRLF at the end of the value removed.
  3. Any SP characters at the beginning of the value removed.
  4. Any syntactically correct [RFC2047] encoded sections with a known character set decoded. Any [RFC2047] encoded NUL octets or control characters are dropped from the decoded value. Any text that looks like [RFC2047] syntax but violates [RFC2047] placement or whitespace rules MUST NOT be decoded.
  5. The resulting unicode converted to NFC form.

If any decodings fail, the parser SHOULD insert a unicode replacement character (U+FFFD) and attempt to continue as much as possible.

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the following header fields:

4.1.2.3. Addresses

Type: EmailAddress[]

The header is parsed as an address-list value, as specified in [RFC5322] section 3.4, into the EmailAddress[] type. There is an EmailAddress item for each mailbox parsed from the address-list. Group and comment information is discarded.

The EmailAddress object has the following properties:

Any syntactically correct [RFC2047] encoded sections with a known encoding MUST be decoded, following the same rules as for the Text form.

Parsing SHOULD be best-effort in the face of invalid structure to accommodate invalid messages and semi-complete drafts. EmailAddress objects MAY have an email property that does not conform to the addr-spec form (for example, may not contain an @ symbol).

For example, the following address-list string: 

"  James Smythe" <james@example.com>, Friends:
  jane@example.com, =?UTF-8?Q?John_Sm=C3=AEth?=
  <john@example.com>;

would be parsed as: 

[
  { "name": "James Smythe", "email": "james@example.com" },
  { "name": null, "email": "jane@example.com" },
  { "name": "John Smîth", "email": "john@example.com" }
]

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the following header fields:

4.1.2.4. GroupedAddresses

Type: EmailAddressGroup[]

This is similar to the Addresses form but preserves group information. The header is parsed as an address-list value, as specified in [RFC5322] section 3.4, into the GroupedAddresses[] type. Consecutive mailboxes that are not part of a group are still collected under an EmailAddressGroup object to provide a uniform type.

The EmailAddressGroup object has the following properties:

Any syntactically correct [RFC2047] encoded sections with a known encoding MUST be decoded, following the same rules as for the Text form.

Parsing SHOULD be best-effort in the face of invalid structure to accommodate invalid messages and semi-complete drafts.

For example, the following address-list string: 

"  James Smythe" <james@example.com>, Friends:
  jane@example.com, =?UTF-8?Q?John_Sm=C3=AEth?=
  <john@example.com>;

would be parsed as: 

[
  { "name": null, "addresses": [
    { "name": "James Smythe", "email": "james@example.com" }
  ]},
  { "name": "Friends", "addresses": [
    { "name": null, "email": "jane@example.com" },
    { "name": "John Smîth", "email": "john@example.com" }
  ]}
]

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the same header fields as the Addresses form.

4.1.2.5. MessageIds

Type: String[]|null

The header is parsed as a list of msg-id values, as specified in [RFC5322] section 3.6.4, into the String[] type. CFWS and surrounding angle brackets (<>) are removed. If parsing fails, the value is null.

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the following header fields:

4.1.2.6. Date

Type: Date|null

The header is parsed as a date-time value, as specified in [RFC5322] section 3.3, into the Date type. If parsing fails, the value is null.

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the following header fields:

4.1.2.7. URLs

Type: String[]|null

The header is parsed as a list of URLs, as described in [RFC2369], into the String[] type. Values do not include the surrounding angle brackets or any comments in the header with the URLs. If parsing fails, the value is null.

To prevent obviously nonsense behaviour, which can lead to interoperability issues, this form may only be fetched or set for the following header fields:

4.1.3. Header fields properties

The following low-level Email property is specified for complete access to the header data of the message:

In addition, the client may request/send properties representing individual header fields of the form: 

header:{header-field-name}

Where {header-field-name} means any series of one or more printable ASCII characters (i.e. characters that have values between 33 and 126, inclusive), except colon. The property may also have the following suffixes:

If both suffixes are used, they MUST be specified in the order above. Header field names are matched case-insensitively. The value is typed according to the requested form, or an array of that type if :all is used. If no header fields exist in the message with the requested name, the value is null if fetching a single instance, or the empty array if requesting :all.

As a simple example, if the client requests a property called header:subject, this means find the last header field in the message named "subject" (matched case-insensitively) and return the value in Raw form, or null if no header of this name is found.

For a more complex example, consider the client requesting a property called header:Resent-To:asAddresses:all. This means:

  1. Find all header fields named Resent-To (matched case-insensitively).
  2. For each instance parse the header field value in the Addresses form.
  3. The result is of type EmailAddress[][] – each item in the array corresponds to the parsed value (which is itself an array) of the Resent-To header field instance.

The following convenience properties are also specified for the Email object:

4.1.4. Body parts

These properties are derived from the [RFC5322] message body and its [RFC2045] MIME entities.

A EmailBodyPart object has the following properties:

In addition, the client may request/send EmailBodyPart properties representing individual header fields, following the same syntax and semantics as for the Email object, e.g. header:Content-Type.

The following Email properties are specified for access to the body data of the message:

The exact algorithm for decomposing bodyStructure into textBody, htmlBody and attachments part lists is not mandated, as this is a quality-of-service implementation issue and likely to require workarounds for malformed content discovered over time. However, the following algorithm (expressed here in JavaScript) is suggested as a starting point, based on real-world experience: 

function isInlineMediaType ( type ) {
  return type.startsWith( 'image/' ) ||
         type.startsWith( 'audio/' ) ||
         type.startsWith( 'video/' );
}

function parseStructure ( parts, multipartType, inAlternative,
        htmlBody, textBody, attachments ) {

    // For multipartType == alternative
    let textLength = textBody ? textBody.length : -1;
    let htmlLength = htmlBody ? htmlBody.length : -1;

    for ( let i = 0; i < parts.length; i += 1 ) {
        let part = parts[i];
        let isMultipart = part.type.startsWith( 'multipart/' );
        // Is this a body part rather than an attachment
        let isInline = part.disposition != "attachment" &&
            // Must be one of the allowed body types
            ( part.type == "text/plain" ||
              part.type == "text/html" ||
              isInlineMediaType( part.type ) ) &&
            // If multipart/related, only the first part can be inline
            // If a text part with a filename, and not the first item
            // in the multipart, assume it is an attachment
            ( i === 0 ||
              ( multipartType != "related" &&
                ( isInlineMediaType( part.type ) || !part.name ) ) );

        if ( isMultipart ) {
            let subMultiType = part.type.split( '/' )[1];
            parseStructure( part.subParts, subMultiType,
                inAlternative || ( subMultiType == 'alternative' ),
                htmlBody, textBody, attachments );
        } else if ( isInline ) {
            if ( multipartType == 'alternative' ) {
                switch ( part.type ) {
                case 'text/plain':
                    textBody.push( part );
                    break;
                case 'text/html':
                    htmlBody.push( part );
                    break;
                default:
                    attachments.push( part );
                    break;
                }
                continue;
            } else if ( inAlternative ) {
                if ( part.type == 'text/plain' ) {
                    htmlBody = null;
                }
                if ( part.type == 'text/html' ) {
                    textBody = null;
                }
            }
            if ( textBody ) {
                textBody.push( part );
            }
            if ( htmlBody ) {
                htmlBody.push( part );
            }
            if ( ( !textBody || !htmlBody ) &&
                    isInlineMediaType( part.type ) ) {
                attachments.push( part );
            }
        } else {
            attachments.push( part );
        }
    }

    if ( multipartType == 'alternative' && textBody && htmlBody ) {
        // Found HTML part only
        if ( textLength == textBody.length &&
                htmlLength != htmlBody.length ) {
            for ( let i = htmlLength; i < htmlBody.length; i += 1 ) {
                textBody.push( htmlBody[i] );
            }
        }
        // Found plain text part only
        if ( htmlLength == htmlBody.length &&
                textLength != textBody.length ) {
            for ( let i = textLength; i < textBody.length; i += 1 ) {
                htmlBody.push( textBody[i] );
            }
        }
    }
}

// Usage:
let htmlBody = [];
let textBody = [];
let attachments = [];

parseStructure( [ bodyStructure ], 'mixed', false,
    htmlBody, textBody, attachments );

For instance, consider a message with both text and HTML versions that's then gone through a list software manager that attaches a header/footer. It might have a MIME structure something like: 

multipart/mixed
  text/plain, content-disposition=inline - A
  multipart/mixed
    multipart/alternative
      multipart/mixed
        text/plain, content-disposition=inline - B
        image/jpeg, content-disposition=inline - C
        text/plain, content-disposition=inline - D
      multipart/related
        text/html - E
        image/jpeg - F
    image/jpeg, content-disposition=attachment - G
    application/x-excel - H
    message/rfc822 - J
  text/plain, content-disposition=inline - K

In this case, the above algorithm would decompose this to: 

textBody => [ A, B, C, D, K ]
htmlBody => [ A, E, K ]
attachments => [ C, F, G, H, J ]

4.2. Email/get

Standard "/get" method, with the following additional arguments: 

[ "partId", "blobId", "size", "name", "type", "charset",
  "disposition", "cid", "language", "location" ]

If the standard properties argument is omitted or null, the following default MUST be used instead of "all" properties: 

[ "id", "blobId", "threadId", "mailboxIds", "keywords", "size",
"receivedAt", "messageId", "inReplyTo", "references", "sender", "from",
"to", "cc", "bcc", "replyTo", "subject", "sentAt", "hasAttachment",
"preview", "bodyValues", "textBody", "htmlBody", "attachments" ]

The following properties are expected to be fast to fetch in a quality implementation:

Clients SHOULD take care when fetching any other properties, as there may be significantly longer latency in fetching and returning the data.

As specified above, parsed forms of headers may only be used on appropriate header fields. Attempting to fetch a form that is forbidden (e.g. header:From:asDate) MUST result in the method call being rejected with an invalidArguments error.

Where a specific header is requested as a property, the capitalization of the property name in the response MUST be identical to that used in the request.

4.2.1. Example

Request: 

[[ "Email/get", {
  "ids": [ "f123u456", "f123u457" ],
  "properties": [ "threadId", "mailboxIds", "from", "subject",
    "receivedAt", "header:List-POST:asURLs",
    "htmlBody", "bodyValues" ],
  "bodyProperties": [ "partId", "blobId", "size", "type" ],
  "fetchHTMLBodyValues": true,
  "maxBodyValueBytes": 256
}, "#1" ]]

and response: 

[[ "Email/get", {
  "accountId": "abc",
  "state": "41234123231",
  "list": [
    {
      "id": "f123u457",
      "threadId": "ef1314a",
      "mailboxIds": { "f123": true },
      "from": [{ "name": "Joe Bloggs", "email": "joe@example.com" }],
      "subject": "Dinner on Thursday?",
      "receivedAt": "2013-10-13T14:12:00Z",
      "header:List-POST:asURLs": [
        "mailto:partytime@lists.example.com"
      ],
      "htmlBody": [{
        "partId": "1",
        "blobId": "B841623871",
        "size": 283331,
        "type": "text/html"
      }, {
        "partId": "2",
        "blobId": "B319437193",
        "size": 10343,
        "type": "text/plain"
      }],
      "bodyValues": {
        "1": {
          "isEncodingProblem": false,
          "isTruncated": true,
          "value": "<html><body><p>Hello ..."
        },
        "2": {
          "isEncodingProblem": false,
          "isTruncated": false,
          "value": "-- Sent by your friendly mailing list ..."
        }
      }
    }
  ],
  "notFound": [ "f123u456" ]
}, "#1" ]]

4.3. Email/changes

Standard "/changes" method. If generating intermediate states for a large set of changes, it is recommended that newer changes are returned first, as these are generally of more interest to users.

4.4. Email/query

Standard "/query" method, but with the following additional arguments:

In quality implementations, the query "total" property is expected to be fast to calculate when the filter consists solely of a single inMailbox property, as it is the same as the totalEmails or totalThreads properties (depending on whether collapseThreads is true) of the associated Mailbox object.

4.4.1. Filtering

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

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:

4.4.2. Sorting

The following properties MUST be supported for sorting:

The following properties SHOULD be supported for sorting:

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 1.3).

Example sort: 

[{
  "property": "someInThreadHaveKeyword",
  "keyword": "$flagged",
  "isAscending": false
}, {
  "property": "subject",
  "collation": "i;ascii-casemap"
}, {
  "property": "receivedAt",
  "isAscending": false
}]

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

4.4.3. Thread collapsing

When collapseThreads is true, then after filtering and sorting the email list, the list is further winnowed by removing any emails for a thread id that has already been seen (when passing through the list sequentially). A thread will therefore only appear once in the result, at the position of the first email in the list that belongs to the thread (given the current sort/filter).

4.5. Email/queryChanges

Standard "/queryChanges" method, with the following additional arguments:

4.6. Email/set

Standard "/set" method. The Email/set method encompasses:

The format of the keywords/mailboxIds properties means that when updating an email you can either replace the entire set of keywords/mailboxes (by setting the full value of the property) or add/remove individual ones using the JMAP patch syntax (see [I-D.ietf-jmap-core], section 5.3 for the specification and section 5.7 for an example).

Due to the format of the Email object, when creating an email there are a number of ways to specify the same information. To ensure that the RFC5322 email to create is unambiguous, the following constraints apply to Email objects submitted for creation:

Creation attempts that violate any of this SHOULD be rejected with an invalidProperties error, however a server MAY choose to modify the Email (e.g. choose between conflicting headers, use a different content-encoding etc.) to comply with its requirements instead.

The server MAY also choose to set additional headers. If not included, the server MUST generate and set a Message-ID header field in conformance with [RFC5322] section 3.6.4, and a Date header field in conformance with section 3.6.1.

The final RFC5322 email generated may be invalid. For example, if it is a half-finished draft, the "To" field may have a value that does not conform to the required syntax for this header field. The message will be checked for strict conformance when submitted for sending (see the EmailSubmission object description).

Destroying an email removes it from all mailboxes to which it belonged. To just delete an email 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 emails which are also in a mailbox other than trash. For those emails, they SHOULD just remove the Trash mailbox from the email.

For successfully created Email objects, the created response contains the id, blobId, threadId and size properties of the object.

The following extra SetError types are defined:

For create:

For create and update:

4.7. Email/copy

Standard "/copy" method, except only the mailboxIds, keywords and receivedAt properties may be set during the copy. This method cannot modify the RFC5322 representation of an email.

The server MAY forbid two email objects with the same exact [RFC5322] content, or even just with the same [RFC5322] Message-ID, to coexist within an account; if the target account already has the email the copy will be rejected with a standard alreadyExists error.

For successfully copied Email objects, the created response contains the id, blobId, threadId and size properties of the new object.

4.8. Email/import

The Email/import method adds [RFC5322] messages to the set of emails in an account. The server MUST support messages with [RFC6532] EAI headers. The messages must first be uploaded as blobs using the standard upload mechanism. It takes the following arguments:

An EmailImport object has the following properties:

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

The server MAY forbid two email objects with the same exact [RFC5322] content, or even just with the same [RFC5322] Message-ID, to coexist within an account. In this case, it MUST reject attempts to import an email considered a duplicate with an alreadyExists SetError. An existingId property of type Id MUST be included on the error object with the id of the existing email. If duplicates are allowed, the newly created Email object MUST have a separate id and independent mutable properties to the existing object.

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 email cannot be imported because it would take the account over quota, the import should be rejected with an overQuota SetError.

If the blob referenced is not a valid [RFC5322] message, the server MAY modify the message to fix errors (such as removing NUL octets or fixing invalid headers). If it does this, the blobId on the response MUST represent the new representation and therefore be different to the blobId on the EmailImport object. Alternatively, the server MAY reject the import with an invalidEmail SetError.

The response has the following arguments:

The following additional errors may be returned instead of the Email/import response:

stateMismatch: An ifInState argument was supplied and it does not match the current state.

4.9. Email/parse

This method allows you to parse blobs as [RFC5322] messages to get Email objects. The server MUST support messages with [RFC6532] EAI headers. This can be used to parse and display attached emails without having to import them as top-level email objects in the mail store in their own right.

The following metadata properties on the Email objects will be null if requested:

The threadId property of the Email MAY be present if the server can calculate which thread the Email would be assigned to were it to be imported. Otherwise, this too is null if fetched.

The Email/parse method takes the following arguments:

The response has the following arguments:

As specified above, parsed forms of headers may only be used on appropriate header fields. Attempting to fetch a form that is forbidden (e.g. header:From:asDate) MUST result in the method call being rejected with an invalidArguments error.

Where a specific header is requested as a property, the capitalization of the property name in the response MUST be identical to that used in the request.

4.10. Examples

A client logs in for the first time. It first fetches the set of mailboxes. Now it will display the inbox to the user, which we will presume has mailbox id "fb666a55". The inbox may be (very!) large, but the user's screen is only so big, so the client will just load the start and then can load in more as necessary. The client sends this request: 

[[ "Email/query",{
  "accountId": "ue150411c",
  "filter": {
    "inMailbox": "fb666a55"
  },
  "sort": [{
    "isAscending": false,
    "property": "receivedAt"
  }],
  "collapseThreads": true,
  "position": 0,
  "limit": 30,
  "calculateTotal": true
}, "0" ],
[ "Email/get", {
  "accountId": "ue150411c",
  "#ids": {
    "resultOf": "0",
    "name": "Email/query",
    "path": "/ids"
  },
  "properties": [
    "threadId"
  ]
}, "1" ],
[ "Thread/get", {
  "accountId": "ue150411c",
  "#ids": {
    "resultOf": "1",
    "name": "Email/get",
    "path": "/list/*/threadId"
  }
}, "2" ],
[ "Email/get", {
  "accountId": "ue150411c",
  "#ids": {
    "resultOf": "2",
    "name": "Thread/get",
    "path": "/list/*/emailIds"
  },
  "properties": [
    "threadId",
    "mailboxIds",
    "keywords",
    "hasAttachment",
    "from",
    "subject",
    "receivedAt",
    "size",
    "preview"
  ]
}, "3" ]]

Let's break down the 4 method calls to see what they're doing:

"0": This asks the server for the ids of the first 30 Email objects in the inbox, sorted newest first, ignoring messages from the same thread as a newer message in the mailbox (i.e. it is the first 30 unique threads).

"1": Now we use a back-reference to fetch the thread ids for each of these email ids.

"2": Another back-reference fetches the Thread object for each of these thread ids.

"3": Finally, we fetch the information we need to display the mailbox listing (but no more!) for every message in each of these 30 threads. The client may aggregate this data for display, for example showing the thread as "flagged" if any of the messages in it contain the $flagged keyword.

The response from the server may look something like this: 

[[ "Email/query", {
  "accountId": "ue150411c",
  "queryState": "09aa9a075588-780599:0",
  "canCalculateChanges": true,
  "position": 0,
  "total": 115,
  "ids": [ "Ma783e5cdf5f2deffbc97930a",
    "M9bd17497e2a99cb345fc1d0a", ... ]
}, "0" ],
[ "Email/get", {
  "accountId": "ue150411c",
  "state": "780599",
  "list": [{
    "id": "Ma783e5cdf5f2deffbc97930a",
    "threadId": "T36703c2cfe9bd5ed"
  }, {
    "id": "M9bd17497e2a99cb345fc1d0a",
    "threadId": "T0a22ad76e9c097a1"
  }, ... ],
  "notFound": []
}, "1" ],
[ "Thread/get", {
  "accountId": "ue150411c",
  "state": "22a8728b",
  "list": [{
    "id": "T36703c2cfe9bd5ed",
    "emailIds": [ "Ma783e5cdf5f2deffbc97930a" ]
  }, {
    "id": "T0a22ad76e9c097a1",
    "emailIds": [ "M3b568670a63e5d100f518fa5",
      "M9bd17497e2a99cb345fc1d0a" ]
  },  ... ],
  "notFound": []
}, "2" ],
[ "Email/get", {
  "accountId": "ue150411c",
  "state": "780599",
  "list": [{
    "id": "Ma783e5cdf5f2deffbc97930a",
    "threadId": "T36703c2cfe9bd5ed",
    "mailboxIds": {
      "fb666a55": true
    },
    "keywords": {
      "$seen": true,
      "$flagged": true
    },
    "hasAttachment": true,
    "from": [{
      "email": "jdoe@example.com",
      "name": "Jane Doe"
    }],
    "subject": "The Big Reveal",
    "receivedAt": "2018-06-27T00:20:35Z",
    "size": 175047,
    "preview": "As you may be aware, we are required to prepare a
      presentation where we wow a panel of 5 random members of the
      public, on or before 30 June each year. We have drafted …"
  },
  ...
  ],
  "notFound": []
}, "3" ]]

Now, on another device the user marks the first message as unread, sending this API request: 

[[ "Email/set", {
  "accountId": "ue150411c",
  "update": {
    "Ma783e5cdf5f2deffbc97930a": {
      "keywords/$seen": null
    }
  }
}, "0" ]]

The server applies this and sends the success response: 

[[ "Email/set", {
  "accountId": "ue150411c",
  "oldState": "780605",
  "newState": "780606",
  "updated": {
    "Ma783e5cdf5f2deffbc97930a": null
  },
  ...
}, "0" ]]

The user also deletes a few messages, and then a new message arrives.

Back on our original machine, we receive a push update that the state string for Email is now "780800". As this does not match the client's current state, it issues a request for the changes: 

[[ "Email/changes", {
  "accountId": "ue150411c",
  "sinceState": "780605",
  "maxChanges": 50
}, "3" ],
[ "Email/queryChanges", {
  "accountId": "ue150411c",
  "filter": {
    "inMailbox": "fb666a55"
  },
  "sort": [{
    "property": "receivedAt",
    "isAscending": false
  }],
  "collapseThreads": true,
  "sinceQueryState": "09aa9a075588-780599:0",
  "upToId": "Mc2781d5e856a908d8a35a564",
  "maxChanges": 25,
  "calculateTotal": true
}, "11" ]]

The response: 

[[ "Email/changes", {
  "accountId": "ue150411c",
  "oldState": "780605",
  "newState": "780800",
  "hasMoreChanges": false,
  "created": [ "Me8de6c9f6de198239b982ea2" ],
  "updated": [ "Ma783e5cdf5f2deffbc97930a" ],
  "destroyed": [ "M9bd17497e2a99cb345fc1d0a", ... ]
}, "3" ],
[ "Email/queryChanges", {
  "accountId": "ue150411c",
  "oldQueryState": "09aa9a075588-780599:0",
  "newQueryState": "e35e9facf117-780615:0",
  "added": [{
    "id": "Me8de6c9f6de198239b982ea2",
    "index": 0
  }],
  "removed": [ "M9bd17497e2a99cb345fc1d0a" ],
  "total": 115
}, "11" ]]

The client can update its local cache of the query results by removing "M9bd17497e2a99cb345fc1d0a" and then splicing in "Me8de6c9f6de198239b982ea2" at position 0. As it does not have the data for this new email, it will then fetch it (it also could have done this in the same request using back-references).

It knows something has changed about "Ma783e5cdf5f2deffbc97930a", so it will refetch the mailboxes and keywords (the only mutable properties) for this email too.

The user composes a new message and saves a draft. The client sends: 

[[ "Email/set", {
  "accountId": "ue150411c",
  "create": {
    "k1546": {
      "mailboxIds": {
        "2ea1ca41b38e": true
      },
      "keywords": {
        "$seen": true,
        "$draft": true
      },
      "from": [{
        "name": "Joe Bloggs",
        "email": "joe@example.com"
      }],
      "to": [{
        "name": "John",
        "email": "john@example.com"
      }],
      "subject": "World domination",
      "receivedAt": "2018-07-10T01:05:08Z",
      "sentAt": "2018-07-10T11:05:08+10:00",
      "bodyStructure": {
        "type": "multipart/alternative",
        "subParts": [{
          "partId": "a49d",
          "type": "text/html"
        }, {
          "partId": "bd48",
          "type": "text/plain"
        }]
      },
      "bodyValues": {
        "bd48": {
          "value": "I have the most brilliant plan. Let me tell you
            all about it. What we do is, we",
          "isTruncated": false
        },
        "49db": {
          "value": "<!DOCTYPE html><html><head><title></title>
            <style type=\"text/css\">div{font-size:16px}</style></head>
            <body><div>I have the most brilliant plan. Let me tell you
            all about it. What we do is, we</div></body></html>",
          "isTruncated": false
        }
      }
    }
  }
}, "0" ]]

The server creates the message and sends the success response: 

[[ "Email/set", {
  "accountId": "ue150411c",
  "oldState": "780823",
  "newState": "780839",
  "created": {
    "k1546": {
      "id": "Md45b47b4877521042cec0938",
      "blobId": "Ge8de6c9f6de198239b982ea214e0f3a704e4af74",
      "threadId": "Td957e72e89f516dc",
      "size": 11721
    }
  },
  ...
}, "0" ]]

The client moves this draft to a different account. The only way to do this is via the /copy method. It MUST set a new mailboxIds property, since the current value will not be valid mailbox ids in the destination account: 

[[ "Email/copy", {
  "fromAccountId": "ue150411c",
  "accountId": "u6c6c41ac",
  "create": {
    "k45": {
      "id": "Md45b47b4877521042cec0938",
      "mailboxIds": {
        "75a4c956": true
      }
    }
  },
  "onSuccessDestroyOriginal": true
}, "0" ]]

The server successfully copies the email and deletes the original. Due to the implicit call to "Email/set", there are two responses to the single method call, both with the same method call id: 

[[ "Email/copy", {
  "fromAccountId": "ue150411c",
  "accountId": "u6c6c41ac",
  "oldState": "7ee7e9263a6d",
  "newState": "5a0d2447ed26",
  "created": {
    "k45": {
      "id": "M138f9954a5cd2423daeafa55",
      "blobId": "G6b9fb047cba722c48c611e79233d057c6b0b74e8",
      "threadId": "T2f242ea424a4079a",
      "size": 11721
    }
  },
  "notCreated": null
}, "0" ],
[ "Email/set", {
  "accountId": "ue150411c",
  "oldState": "780839",
  "newState": "780871",
  "destroyed": [ "Md45b47b4877521042cec0938" ],
  ...
}, "0" ]]

5. Search snippets

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 email. Search snippets represent this data.

A SearchSnippet object has the following properties:

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 and preview properties.

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

The following JMAP method is supported:

5.1. SearchSnippet/get

To fetch search snippets, make a call to SearchSnippet/get. It takes the following arguments:

The response has the following arguments:

As the search snippets are derived from the message content and the algorithm for doing so could change over time, fetching the same snippets a second time MAY return a different result. However, the previous value is not considered incorrect, so there is no state string or update mechanism needed.

The following standard errors may be returned instead of the searchSnippets response:

requestTooLarge: The number of emailIds requested by the client exceeds the maximum number the server is willing to process in a single method call.

unsupportedFilter: The server is unable to process the given filter for any reason.

5.2. Example

Here we did an Email/query to search for any email in the account containing the word "foo", now we are fetching the search snippets for some of the ids that were returned in the results: 

[[ "SearchSnippet/get", {
  "accountId": "ue150411c",
  "filter": {
    "text": "foo"
  },
  "emailIds": [
    "M44200ec123de277c0c1ce69c",
    "M7bcbcb0b58d7729686e83d99",
    "M28d12783a0969584b6deaac0",
    ...
  ]
}, "0" ]]

Example response: 

[[ "SearchSnippet/get", {
  "accountId": "ue150411c",
  "list": [{
      "emailId": "M44200ec123de277c0c1ce69c",
      "subject": null,
      "preview": null
  }, {
      "emailId": "M7bcbcb0b58d7729686e83d99",
      "subject": "The <mark>Foo</mark>sball competition",
      "preview": "...year the <mark>foo</mark>sball competition will
        be held in the Stadium de ..."
  }, {
      "emailId": "M28d12783a0969584b6deaac0",
      "subject": null,
      "preview": "...the <mark>Foo</mark>/bar method results often
        returns &lt;1 widget rather than the complete..."
  },
  ...
  ],
  "notFound": null
}, "0" ]]

6. Identities

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

See the "Addresses" header form description in the Email object for the definition of EmailAddress.

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. Identity/get

Standard "/get" method. The ids argument may be null to fetch all at once.

6.2. Identity/changes

Standard "/changes" method.

6.3. Identity/set

Standard "/set" method. The following extra SetError types are defined:

For create:

6.4. Example

Request: 

[ "Identity/get", {
  "accountId": "acme"
}, "0" ]

with response: 

[ "Identity/get", {
  "accountId": "acme",
  "state": "99401312ae-11-333",
  "list": [
    {
      "id": "XD-3301-222-11_22AAz",
      "name": "Joe Bloggs",
      "email": "joe@example.com",
      "replyTo": null,
      "bcc": [{
        "name": null,
        "email": "joe+archive@example.com"
      }],
      "textSignature": "-- \nJoe Bloggs\nMaster of Email",
      "htmlSignature": "<div><b>Joe Bloggs</b></div>
        <div>Master of Email</div>",
      "mayDelete": false
    },
    {
      "id": "XD-9911312-11_22AAz",
      "name": "Joe B",
      "email": "*@example.com",
      "replyTo": null,
      "bcc": null,
      "textSignature": "",
      "htmlSignature": "",
      "mayDelete": true
    }
  ],
  "notFound": []
}, "0" ]

7. Email submission

An EmailSubmission object represents the submission of an email for delivery to one or more recipients. It has the following properties: 

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

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

JMAP servers MAY choose not to expose DSN and MDN responses as Email objects if they correlate to an EmailSubmission 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 EmailSubmission object.

For efficiency, a server MAY destroy EmailSubmission objects a certain amount of time after the email is successfully sent or it has finished retrying sending the email. 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:

7.1. EmailSubmission/get

Standard "/get" method.

7.2. EmailSubmission/changes

Standard "/changes" method.

7.3. EmailSubmission/query

Standard "/query" method.

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

An EmailSubmission object matches the FilterCondition if and only if all of the given conditions match. If zero properties are specified, it is automatically true for all objects.

The following properties MUST be supported for sorting:

7.4. EmailSubmission/queryChanges

Standard "/queryChanges" method.

7.5. EmailSubmission/set

Standard "/set" method, with the following two extra arguments:

A single implicit Email/set call MUST be made after all EmailSubmission create/update/destroy requests have been processed to perform any changes requested in these two arguments. The response to this MUST be returned after the EmailSubmission/set response.

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

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

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

If the email to be sent is larger than the server supports sending, a standard tooLarge SetError MUST be returned. A maxSize UnsignedInt property MUST be present on the SetError specifying the maximum size of an email that may be sent, in octets.

If the email or identity id given cannot be found, the submission creation is rejected with a standard invalidProperties SetError.

The following extra SetError types are defined:

For create:

For update:

7.5.1. Example

The following example presumes a draft of the message to be sent has already been saved, and its Email id is "M7f6ed5bcfd7e2604d1753f6c". This call then sends the email immediately, and if successful removes the draft flag and moves it from the Drafts folder (which has Mailbox id "7cb4e8ee-df87-4757-b9c4-2ea1ca41b38e") to the Sent folder (which we presume has Mailbox id "73dbcb4b-bffc-48bd-8c2a-a2e91ca672f6"). 

[[ "EmailSubmission/set", {
  "accountId": "ue411d190",
  "create": {
    "k1490": {
      "identityId": "I64588216",
      "emailId": "M7f6ed5bcfd7e2604d1753f6c",
      "envelope": {
        "mailFrom": {
          "email": "john@example.com",
          "parameters": null
        },
        "rcptTo": [{
          "email": "jane@example.com",
          "parameters": null
        },
        ...
        ]
      }
    }
  },
  "onSuccessUpdateEmail": {
    "#k1490": {
      "mailboxIds/7cb4e8ee-df87-4757-b9c4-2ea1ca41b38e": null,
      "mailboxIds/73dbcb4b-bffc-48bd-8c2a-a2e91ca672f6": true,
      "keywords/$draft": null
    }
  }
}, "0" ]]

A successful response might look like this. Note there are two responses due to the implicit Email/set call, but both have the same method call id as they are due to the same call in the request: 

[[ "EmailSubmission/set", {
  "accountId": "ue411d190",
  "oldState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
  "newState": "355421f6-8aed-4cf4-a0c4-7377e951af36",
  "created": {
    "k1490": {
      "id": "ES-3bab7f9a-623e-4acf-99a5-2e67facb02a0"
    }
  }
}, "0" ],
[ "Email/set", {
  "accountId": "ue411d190",
  "oldState": "778193",
  "newState": "778197",
  "updated": {
      "M7f6ed5bcfd7e2604d1753f6c": null
  }
}, "0" ]]

Suppose instead an admin has removed sending rights for the user, and so the email submission is rejected with a "forbiddenToSend" error. The description argument of the error is intended for display to the user, so should be localised appropriately. Let's suppose the request was sent with an Accept-Language header like this: 

Accept-Language: de;q=0.9,en;q=0.8

The server should attempt to choose the best localisation from those it has available based on the Accept-Language header, as described in [I-D.ietf-jmap-core], section 3.7. If the server has English, French and German translations it would choose German as the preferred language and return a response like this: 

[[ "EmailSubmission/set", {
  "accountId": "ue411d190",
  "oldState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
  "newState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
  "notCreated": {
    "k1490": {
      "type": "forbiddenToSend",
      "description": "Verzeihung, wegen verdächtiger Aktivitäten Ihres Benutzerkontos haben wir den Versand von Nachrichten gesperrt. Bitte wenden Sie sich für Hilfe an unser Support Team."
    }
  }
}, "0" ]]

8. Vacation response

A vacation response automatically sends a reply to messages sent to a particular account, to inform the original sender that their message may not be read for some time. Automated message sending can produce undesirable behaviour. To avoid this, implementors MUST follow the recommendations set forth in [RFC3834].

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

The following JMAP methods are supported:

8.1. VacationResponse/get

Standard "/get" method.

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

8.2. VacationResponse/set

Standard "/set" method.

9. Security considerations

All security considerations of JMAP ([I-D.ietf-jmap-core]) apply to this specification.

9.1. EmailBodyPart value

Service providers typically perform security filtering on incoming email and it's important that the detection of content-type and charset for the security filter aligns with the heuristics performed by JMAP servers. Servers that apply heuristics to determine the content-type or charset for EmailBodyValue SHOULD document the heuristics and provide a mechanism to turn them off in the event they are misaligned with the security filter used at a particular mailbox host.

Automatic conversion of charsets that allow hidden channels for ASCII text, such as UTF-7, have been problematic for security filters in the past so server implementations can mitigate this risk by having such conversions off-by-default and/or separately configurable.

To allow the client to restrict the volume of data it can receive in response to a request, a maximum length may be requested for the data returned for a textual body part. However, truncating the data may change the semantic meaning, for example truncating a URL changes its location. Servers that scan for links to malicious sites should take care to either ensure truncation is not at a semantically significant point, or to rescan the truncated value for malicious content before returning it.

9.2. HTML email display

HTML message bodies provide richer formatting for emails but present a number of security challenges, especially when embedded in a webmail context in combination with interface HTML. Clients that render HTML email should make careful consideration of the potential risks, including:

There are a number of ways clients can mitigate these issues, and a defence-in-depth approach that uses a combination of techniques will provide the strongest security.

Subtle differences in parsing of HTML can introduce security flaws: to filter with 100% accuracy you need to use the same parser when sanitizing that the HTML rendering engine will use.

As highly complex software components, HTML rendering engines increase the attack surface of a client considerably, especially when being used to process untrusted, potentially malicious content. Serious bugs have been found in image decoders, JavaScript engines and HTML parsers in the past, which could lead to full system compromise. Clients using an engine should ensure they get the latest version and continue to incorporate any security patches released by the vendor.

9.3. Email submission

SMTP submission servers [RFC6409] use a number of mechanisms to mitigate damage caused by compromised user accounts and end-user systems including rate limiting, anti-virus/anti-spam milters (mail filters) and other technologies. The technologies work better when they have more information about the client connection. If JMAP email submission is implemented as a proxy to an SMTP Submission server, it is useful to communicate this information from the JMAP proxy to the submission server. The de-facto [XCLIENT] extension to SMTP can be used to do this, but use of an authenticated channel is recommended to limit use of that extension to explicitly authorized proxies.

JMAP servers that proxy to an SMTP Submission server SHOULD allow use of the submissions port [RFC8314] and SHOULD implement SASL PLAIN over TLS [RFC4616] and/or TLS client certificate authentication with SASL EXTERNAL [RFC4422] appendix A. Implementation of a mechanism similar to SMTP XCLIENT is strongly encouraged.

In the event the JMAP server directly relays mail to SMTP servers in other administrative domains, then implementation of the de-facto [milter] protocol is strongly encouraged to integrate with third-party products that address security issues including anti-virus/anti-spam, reputation protection, compliance archiving, and data loss prevention. Proxying to a local SMTP Submission server may be a simpler way to provide such security services.

9.4. Partial account access

A user may only have permission to access a subset of the data that exists in an account. To avoid leaking any unauthorised information, in such a situation the server MUST treat any data the user does not have permission to access the same as if it did not exist.

For example, suppose user A has an account with two mailboxes, Inbox and Sent, but only shares the Inbox with user B. In this case, when user B fetches mailboxes for this account, the server MUST behave as though the Sent mailbox did not exist. Similarly when querying or fetching Email objects, it MUST treat any messages that just belong to the Sent mailbox as though they did not exist. Fetching Thread objects MUST only return ids for Email objects the user has permission to access; if none, the Thread again MUST be treated the same as if it did not exist.

10. IANA considerations

10.1. JMAP capability registration for "mail"

IANA will register the "mail" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:mail

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, section 9

10.2. JMAP capability registration for "submission"

IANA will register the "submission" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:submission

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, section 9

10.3. JMAP capability registration for "vacationresponse"

IANA will register the "vacationresponse" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:vacationresponse

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, section 9

10.4. IMAP and JMAP keywords registry

This document makes two changes to the IMAP keywords registry as defined in [RFC5788].

First, the name of the registry is changed to the "IMAP and JMAP keywords Registry".

Second, a scope column is added to the template and registry indicating whether a keyword applies to IMAP-only, JMAP-only, both, or reserved. All keywords presently in the IMAP keyword registry will be marked with a scope of both. The "reserved" status can be used to prevent future registration of a name that would be confusing if registered. Registration of keywords with scope 'reserved' omit most fields in the registration template (see registration of $recent below for an example); such registrations are intended to be infrequent.

IMAP clients MAY silently ignore any keywords marked JMAP-only or reserved in the event they appear in protocol. JMAP clients MAY silently ignore any keywords marked IMAP-only or reserved in the event they appear in protocol.

New JMAP-only keywords are registered in the following sub-sections. These keywords correspond to IMAP system keywords and are thus not appropriate for use in IMAP. These keywords can not be subsequently registered for use in IMAP except via standards action.

10.4.1. Registration of JMAP keyword '$draft'

This registers the JMAP-only keyword '$draft' in the "IMAP and JMAP keywords Registry".

Keyword name: $draft

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the message as a draft the user is composing. This is the JMAP equivalent of the IMAP \Draft flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action: Automatic. If the account has a mailbox marked with the \Drafts special use [RFC6154], setting this flag MAY cause the message to appear in that mailbox automatically. Certain JMAP computed values such as unreadEmails will change as a result of changing this flag. In addition, mail clients typically will present draft messages in a composer window rather than a viewer window.

When/by whom the keyword is set/cleared: This is typically set by a JMAP client when referring to a draft message. One model for draft emails would result in clearing this flag in an EmailSubmission/set operation with an onSuccessUpdateEmail attribute. In a mailstore shared by JMAP and IMAP, this is also set and cleared as necessary so it matches the IMAP \Draft flag.

Related keywords: None

Related IMAP/JMAP Capabilities: SPECIAL-USE [RFC6154]

Security Considerations: A server implementing this keyword as a shared keyword may disclose that a user considers the message a draft message. This information would be exposed to other users with read permission for the mailbox keywords.

Published specification (recommended): this document

Person & email address to contact for further information: (editor-contact-goes-here)

Intended usage: COMMON

Owner/Change controller: IESG

10.4.2. Registration of JMAP keyword '$seen'

This registers the JMAP-only keyword '$seen' in the "IMAP and JMAP keywords Registry".

Keyword name: $seen

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the message as read. This is the JMAP equivalent of the IMAP \Seen flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action: Advisory. However, certain JMAP computed values such as unreadEmails will change as a result of changing this flag.

When/by whom the keyword is set/cleared: This is set by a JMAP client when it presents the message content to the user; clients often offer an option to clear this flag. In a mailstore shared by JMAP and IMAP, this is also set and cleared as necessary so it matches the IMAP \Seen flag.

Related keywords: None

Related IMAP/JMAP Capabilities: None

Security Considerations: A server implementing this keyword as a shared keyword may disclose that a user considers the message to have been read. This information would be exposed to other users with read permission for the mailbox keywords.

Published specification (recommended): this document

Person & email address to contact for further information: (editor-contact-goes-here)

Intended usage: COMMON

Owner/Change controller: IESG

10.4.3. Registration of JMAP keyword '$flagged'

This registers the JMAP-only keyword '$flagged' in the "IMAP and JMAP keywords Registry".

Keyword name: $flagged

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the message as flagged for urgent/special attention. This is the JMAP equivalent of the IMAP \Flagged flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action: Automatic. If the account has a mailbox marked with the \Flagged special use [RFC6154], setting this flag MAY cause the message to appear in that mailbox automatically.

When/by whom the keyword is set/cleared: JMAP clients typically allow a user to set/clear this flag as desired. In a mailstore shared by JMAP and IMAP, this is also set and cleared as necessary so it matches the IMAP \Flagged flag.

Related keywords: None

Related IMAP/JMAP Capabilities: SPECIAL-USE [RFC6154]

Security Considerations: A server implementing this keyword as a shared keyword may disclose that a user considers the message as flagged for urgent/special attention. This information would be exposed to other users with read permission for the mailbox keywords.

Published specification (recommended): this document

Person & email address to contact for further information: (editor-contact-goes-here)

Intended usage: COMMON

Owner/Change controller: IESG

10.4.4. Registration of JMAP keyword '$answered'

This registers the JMAP-only keyword '$answered' in the "IMAP and JMAP keywords Registry".

Keyword name: $answered

Scope: JMAP-only

Purpose (description): This is set when the message has been answered.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action: Advisory.

When/by whom the keyword is set/cleared: JMAP clients typically set this when submitting a reply or answer to the message. It may be set by the EmailSubmission/set operation with an onSuccessUpdateEmail attribute. In a mailstore shared by JMAP and IMAP, this is also set and cleared as necessary so it matches the IMAP \Answered flag.

Related keywords: None

Related IMAP/JMAP Capabilities: None

Security Considerations: A server implementing this keyword as a shared keyword may disclose that a user has replied to a message. This information would be exposed to other users with read permission for the mailbox keywords.

Published specification (recommended): this document

Person & email address to contact for further information: (editor-contact-goes-here)

Intended usage: COMMON

Owner/Change controller: IESG

10.4.5. Registration of '$recent' keyword

This registers the keyword '$recent' in the "IMAP and JMAP keywords Registry".

Keyword name: $recent

Scope: reserved

Purpose (description): This keyword is not used to avoid confusion with the IMAP \Recent system flag.

Published specification (recommended): this document

Person & email address to contact for further information: (editor-contact-goes-here)

Owner/Change controller: IESG

10.5. Registration of "inbox" role in

This registers the JMAP-only "inbox" attribute in the "IMAP Mailbox Name Attributes Registry", as established in [RFC8457].

Attribute Name: Inbox

Description: New mail is delivered here by default.

Reference: This document, section 10.5.

Usage Notes: JMAP only

10.6. JMAP Error Codes registry

The following sub-sections register several new error codes in the JMAP Error Codes registry, as defined in [I-D.ietf-jmap-core].

10.6.1. mailboxHasChild

JMAP Error Code: mailboxHasChild

Intended use: common

Change controller: IETF

Reference: This document, section 2.5

10.6.2. mailboxHasEmail

JMAP Error Code: mailboxHasEmail

Intended use: common

Change controller: IETF

Reference: This document, section 2.5

10.6.3. blobNotFound

JMAP Error Code: blobNotFound

Intended use: common

Change controller: IETF

Reference: This document, section 4.6

10.6.4. tooManyKeywords

JMAP Error Code: tooManyKeywords

Intended use: common

Change controller: IETF

Reference: This document, section 4.6

10.6.5. tooManyMailboxes

JMAP Error Code: tooManyMailboxes

Intended use: common

Change controller: IETF

Reference: This document, section 4.6

10.6.6. invalidEmail

JMAP Error Code: invalidEmail

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

10.6.7. tooManyRecipients

JMAP Error Code: tooManyRecipients

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

10.6.8. noRecipients

JMAP Error Code: noRecipients

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

10.6.9. invalidRecipients

JMAP Error Code: invalidRecipients

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

10.6.10. forbiddenMailFrom

JMAP Error Code: forbiddenMailFrom

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

10.6.11. forbiddenFrom

JMAP Error Code: forbiddenFrom

Intended use: common

Change controller: IETF

Reference: This document, sections 6.3 and 7.5

10.6.12. forbiddenToSend

JMAP Error Code: forbiddenToSend

Intended use: common

Change controller: IETF

Reference: This document, section 7.5

11. References

11.1. Normative References

[HTML] Faulkner, S., Eicholz, A., Leithead, T., Danilo, A. and S. Moon, "HTML 5.2", 2017.
[I-D.ietf-jmap-core] Jenkins, N. and C. Newman, "JSON Meta Application Protocol", Internet-Draft draft-ietf-jmap-core-14, January 2019.
[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.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996.
[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.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations", RFC 2231, DOI 10.17487/RFC2231, November 1997.
[RFC2369] Neufeld, G. and J. Baer, "The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields", RFC 2369, DOI 10.17487/RFC2369, July 1998.
[RFC2392] Levinson, E., "Content-ID and Message-ID Uniform Resource Locators", RFC 2392, DOI 10.17487/RFC2392, August 1998.
[RFC2557] Palme, J., Hopmann, A. and N. Shelness, "MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)", RFC 2557, DOI 10.17487/RFC2557, March 1999.
[RFC2852] Newman, D., "Deliver By SMTP Service Extension", RFC 2852, DOI 10.17487/RFC2852, June 2000.
[RFC3282] Alvestrand, H., "Content Language Headers", RFC 3282, DOI 10.17487/RFC3282, May 2002.
[RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)", RFC 3461, DOI 10.17487/RFC3461, January 2003.
[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes", RFC 3463, DOI 10.17487/RFC3463, January 2003.
[RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format for Delivery Status Notifications", RFC 3464, DOI 10.17487/RFC3464, January 2003.
[RFC3834] Moore, K., "Recommendations for Automatic Responses to Electronic Mail", RFC 3834, DOI 10.17487/RFC3834, August 2004.
[RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", RFC 4314, DOI 10.17487/RFC4314, December 2005.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and Security Layer (SASL)", RFC 4422, DOI 10.17487/RFC4422, June 2006.
[RFC4616] Zeilenga, K., "The PLAIN Simple Authentication and Security Layer (SASL) Mechanism", RFC 4616, DOI 10.17487/RFC4616, August 2006.
[RFC4865] White, G. and G. Vaudreuil, "SMTP Submission Service Extension for Future Message Release", RFC 4865, DOI 10.17487/RFC4865, May 2007.
[RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008.
[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.
[RFC5256] Crispin, M. and K. Murchison, "Internet Message Access Protocol - SORT and THREAD Extensions", RFC 5256, DOI 10.17487/RFC5256, June 2008.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, October 2008.
[RFC5322] Resnick, P., "Internet Message Format", RFC 5322, DOI 10.17487/RFC5322, October 2008.
[RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", RFC 5788, DOI 10.17487/RFC5788, March 2010.
[RFC6154] Leiba, B. and J. Nicolson, "IMAP LIST Extension for Special-Use Mailboxes", RFC 6154, DOI 10.17487/RFC6154, March 2011.
[RFC6409] Gellens, R. and J. Klensin, "Message Submission for Mail", STD 72, RFC 6409, DOI 10.17487/RFC6409, November 2011.
[RFC6532] Yang, A., Steele, S. and N. Freed, "Internationalized Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 2012.
[RFC6533] Hansen, T., Newman, C. and A. Melnikov, "Internationalized Delivery Status and Disposition Notifications", RFC 6533, DOI 10.17487/RFC6533, February 2012.
[RFC6710] Melnikov, A. and K. Carlberg, "Simple Mail Transfer Protocol Extension for Message Transfer Priorities", RFC 6710, DOI 10.17487/RFC6710, August 2012.
[RFC8098] Hansen, T. and A. Melnikov, "Message Disposition Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, February 2017.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018.
[RFC8457] Leiba, B., "IMAP "$Important" Keyword and "\Important" Special-Use Attribute", RFC 8457, DOI 10.17487/RFC8457, September 2018.
[RFC8474] Gondwana, B., "IMAP Extension for Object Identifiers", RFC 8474, DOI 10.17487/RFC8474, September 2018.

11.2. Informative References

[milter] Unknown, "Postfix before-queue Milter support", 2019.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003.
[XCLIENT] Unknown, "Postfix XCLIENT Howto", 2019.

Authors' Addresses

Neil Jenkins FastMail PO Box 234, Collins St West Melbourne, VIC 8007 Australia EMail: neilj@fastmailteam.com URI: https://www.fastmail.com
Chris Newman Oracle 440 E. Huntington Dr., Suite 400 Arcadia, CA 91006 United States of America EMail: chris.newman@oracle.com