---
title: "POST /users/{userId}/messages"
method: POST
path: "/users/{userId}/messages"
tags: ["users"]
---

# POST /users/{userId}/messages

`POST /users/{userId}/messages`

Directly inserts a message into only this user's mailbox similar to `IMAP APPEND`, bypassing most scanning and classification. Does not send a message.

## Path parameters

- `userId` string, required

## Query parameters

- `$.xgafv` '1' | '2' — V1 error format
- `access_token` string
- `alt` 'json' | 'media' | 'proto' — Data format for response
- `callback` string
- `fields` string
- `key` string
- `oauth_token` string
- `prettyPrint` boolean
- `quotaUser` string
- `upload_protocol` string
- `uploadType` string
- `deleted` boolean
- `internalDateSource` 'receivedTime' | 'dateHeader'

## Request body

- Message — An email message
  - `snippet` string — A short part of the message text
  - `threadId` string — The ID of the thread the message belongs to. To add a message or draft to a thread, the following criteria must be met: 1. The requested `threadId` must be specified on the `Message` or `Draft.Message` you supply with your request. 2. The `References` and `In-Reply-To` headers must be set in compliance with the [RFC 2822](https://tools.ietf.org/html/rfc2822) standard. 3. The `Subject` headers must match.
  - `labelIds` string[] — List of IDs of labels applied to this message
  - `payload` MessagePart — A single MIME message part
    - `headers` MessagePartHeader[] — List of headers on this message part. For the top-level message part, representing the entire message payload, it will contain the standard RFC 2822 email headers such as `To`, `From`, and `Subject`
      - `name` string — The name of the header before the `:` separator. For example, `To`
      - `value` string — The value of the header after the `:` separator. For example, `someuser@example.com`
    - `filename` string — The filename of the attachment. Only present if this message part represents an attachment
    - `partId` string — The immutable ID of the message part
    - `parts` MessagePart[] — The child MIME message parts of this part. This only applies to container MIME message parts, for example `multipart/*`. For non- container MIME message part types, such as `text/plain`, this field is empty. For more information, see RFC 1521
    - `mimeType` string — The MIME type of the message part
    - `body` MessagePartBody — The body of a single MIME message part
      - `data` string, byte — The body data of a MIME message part as a base64url encoded string. May be empty for MIME container types that have no message body or when the body data is sent as a separate attachment. An attachment ID is present if the body data is contained in a separate attachment
      - `size` integer — Number of bytes for the message part data (encoding notwithstanding)
      - `attachmentId` string — When present, contains the ID of an external attachment that can be retrieved in a separate `messages.attachments.get` request. When not present, the entire content of the message part body is contained in the data field
  - `historyId` string, uint64 — The ID of the last history record that modified this message
  - `raw` string, byte — The entire email message in an RFC 2822 formatted and base64url encoded string. Returned in `messages.get` and `drafts.get` responses when the `format=RAW` parameter is supplied
  - `id` string — The immutable ID of the message
  - `sizeEstimate` integer — Estimated size in bytes of the message
  - `internalDate` string, int64 — The internal message creation timestamp (epoch ms), which determines ordering in the inbox. For normal SMTP-received email, this represents the time the message was originally accepted by Google, which is more reliable than the `Date` header. However, for API-migrated mail, it can be configured by client to be based on the `Date` header

## Response `200`

Successful response

- Message — An email message
  - `snippet` string — A short part of the message text
  - `threadId` string — The ID of the thread the message belongs to. To add a message or draft to a thread, the following criteria must be met: 1. The requested `threadId` must be specified on the `Message` or `Draft.Message` you supply with your request. 2. The `References` and `In-Reply-To` headers must be set in compliance with the [RFC 2822](https://tools.ietf.org/html/rfc2822) standard. 3. The `Subject` headers must match.
  - `labelIds` string[] — List of IDs of labels applied to this message
  - `payload` MessagePart — A single MIME message part
    - `headers` MessagePartHeader[] — List of headers on this message part. For the top-level message part, representing the entire message payload, it will contain the standard RFC 2822 email headers such as `To`, `From`, and `Subject`
      - `name` string — The name of the header before the `:` separator. For example, `To`
      - `value` string — The value of the header after the `:` separator. For example, `someuser@example.com`
    - `filename` string — The filename of the attachment. Only present if this message part represents an attachment
    - `partId` string — The immutable ID of the message part
    - `parts` MessagePart[] — The child MIME message parts of this part. This only applies to container MIME message parts, for example `multipart/*`. For non- container MIME message part types, such as `text/plain`, this field is empty. For more information, see RFC 1521
    - `mimeType` string — The MIME type of the message part
    - `body` MessagePartBody — The body of a single MIME message part
      - `data` string, byte — The body data of a MIME message part as a base64url encoded string. May be empty for MIME container types that have no message body or when the body data is sent as a separate attachment. An attachment ID is present if the body data is contained in a separate attachment
      - `size` integer — Number of bytes for the message part data (encoding notwithstanding)
      - `attachmentId` string — When present, contains the ID of an external attachment that can be retrieved in a separate `messages.attachments.get` request. When not present, the entire content of the message part body is contained in the data field
  - `historyId` string, uint64 — The ID of the last history record that modified this message
  - `raw` string, byte — The entire email message in an RFC 2822 formatted and base64url encoded string. Returned in `messages.get` and `drafts.get` responses when the `format=RAW` parameter is supplied
  - `id` string — The immutable ID of the message
  - `sizeEstimate` integer — Estimated size in bytes of the message
  - `internalDate` string, int64 — The internal message creation timestamp (epoch ms), which determines ordering in the inbox. For normal SMTP-received email, this represents the time the message was originally accepted by Google, which is more reliable than the `Date` header. However, for API-migrated mail, it can be configured by client to be based on the `Date` header

---

[API](https://skmtc.net/ballerina-platform/apis/gmail-api.md) · [All operations](https://skmtc.net/ballerina-platform/apis/gmail-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/ballerina-platform/gmail-api/versions/c7f11764507c/schema)