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Schedules a message to be sent to a channel.


Method URL:https://slack.com/api/chat.scheduleMessage
Preferred HTTP method:POST
Accepted content types:application/x-www-form-urlencoded, application/json
Rate limiting:Tier 3
Works with:
Token typeRequired scope(s)
userchat:write:user  chat:write:bot 

This method schedules a message for delivery to a public channel, private channel, or direct message/IM channel at a specified time in the future.


Argument Example Required Description

Authentication token bearing required scopes.


Channel, private group, or DM channel to send message to. Can be an encoded ID, or a name. See below for more details.


Unix EPOCH timestamp of time in future to send the message.

textHello worldRequired

Text of the message to send. See below for an explanation of formatting. This field is usually required, unless you're providing only attachments instead. Provide no more than 40,000 characters or risk truncation.


Pass true to post the message as the authed user, instead of as a bot. Defaults to false. See authorship below.

attachments[{"pretext": "pre-hello", "text": "text-world"}]Optional

A JSON-based array of structured attachments, presented as a URL-encoded string.

blocks[{"type": "section", "text": {"type": "plain_text", "text": "Hello world"}}]Optional

A JSON-based array of structured blocks, presented as a URL-encoded string.


Find and link channel names and usernames.


Change how messages are treated. Defaults to none. See below.


Used in conjunction with thread_ts and indicates whether reply should be made visible to everyone in the channel or conversation. Defaults to false.


Provide another message's ts value to make this message a reply. Avoid using a reply's ts value; use its parent instead.


Pass true to enable unfurling of primarily text-based content.


Pass false to disable unfurling of media content.

This method supports application/json via HTTP POST. Present your token in your request's Authorization header. Learn more.

The post_at arg is a Unix EPOCH timestamp, representing the time the message should post to Slack in the future.

With the exception of the additional post_at argument, this method behaves identically to chat.postMessage. Peruse that page for in-depth documentation on each parameter that this method accepts.

A message must have either text or attachments or both. The text parameter is required unless you provide attachments. You can use both parameters in conjunction with each other to create awesome messages.


You will only be able to schedule a message up to 120 days into the future. If you specify a post_at timestamp beyond this limit, you’ll receive a time_too_far error response.


Typical success response

    "ok": true,
    "channel": "C1H9RESGL",
    "scheduled_message_id": "Q1298393284",
    "post_at": "1562180400",
    "message": {
        "text": "Here's a message for you in the future",
        "username": "ecto1",
        "bot_id": "B19LU7CSY",
        "attachments": [
                "text": "This is an attachment",
                "id": 1,
                "fallback": "This is an attachment's fallback"
        "type": "delayed_message",
        "subtype": "bot_message"

Typical error response if the post_at is invalid (ex. in the past or too far into the future)

    "ok": false,
    "error": "time_in_past"

The response includes the scheduled_message_id assigned to your message. Use it with the chat.deleteScheduledMessage method to delete the message before it is sent.

For details on formatting, usage in threads, and rate limiting, check out chat.postMessage documentation.


You must specify a public channel, private channel, or an IM channel with the channel argument. Each one behaves slightly differently based on the authenticated user's permissions and additional arguments:

Post to a channel

You can either pass the channel's name (#general) or encoded ID (C024BE91L), and the message will be posted to that channel. The channel's ID can be retrieved through the channels.list API method.

Post to a DM

Pass the IM channel's ID (D023BB3L2) or a user's ID (U0G9QF9C6) as the value of channel to post to that IM channel as the app. The IM channel's ID can be retrieved through the im.list API method.

You might receive a channel_not_found error if your app doesn't have permission to enter into an IM with the intended user.


This table lists the expected errors that this method could return. However, other errors can be returned in the case where the service is down or other unexpected factors affect processing. Callers should always check the value of the ok params in the response.


value passed for post_time was invalid.


value passed for post_time was in the past.


value passed for post_time was too far into the future.


Value passed for channel was invalid.


Cannot post user messages to a channel they are not in.


Channel has been archived.


Message text is too long


No message text provided


A workspace preference prevents the authenticated user from posting.


Cannot post any message into a read-only channel.


Cannot post top-level messages into a thread-only channel.


Cannot post thread replies into a non_threadable channel.


Too many attachments were provided with this message. A maximum of 100 attachments are allowed on a message.


Application has posted too many messages, read the Rate Limit documentation for more information


No authentication token provided.


Some aspect of authentication cannot be validated. Either the provided token is invalid or the request originates from an IP address disallowed from making the request.


Authentication token is for a deleted user or workspace.


Authentication token is for a deleted user or workspace or the app has been removed.


The workspace token used in this request does not have the permissions necessary to complete the request. Make sure your app is a member of the conversation it's attempting to post a message to.


The workspace is undergoing an enterprise migration and will not be available until migration is complete.


Administrators have suspended the ability to post a message.


The token used is not granted the specific scope permissions required to complete this request.


The method was called with invalid arguments.


The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.


The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8 iso-8859-1.


The method was called via a POST request with Content-Type application/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.


The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/json application/x-www-form-urlencoded multipart/form-data text/plain.


The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.


The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.


The method was called via a POST request, but the POST data was either missing or truncated.


The server could not complete your operation(s) without encountering a catastrophic error. It's possible some aspect of the operation succeeded before the error was raised.


This table lists the expected warnings that this method will return. However, other warnings can be returned in the case where the service is experiencing unexpected trouble.


The text field of a message should have no more than 40,000 characters. We truncate really long messages.


The method was called via a POST request, and recommended practice for the specified Content-Type is to include a charset parameter. However, no charset was present. Specifically, non-form-data content types (e.g. text/plain) are the ones for which charset is recommended.


The method was called via a POST request, and the specified Content-Type is not defined to understand the charset parameter. However, charset was in fact present. Specifically, form-data content types (e.g. multipart/form-data) are the ones for which charset is superfluous.