---
title: "Slack Message Scheduler for Channels"
description: "Schedule Slack messages with images to public and private channels under the name and picture you choose, with follow-ups posted as thread replies."
canonical_url: "https://postqueen.ai/channels/slack"
markdown_url: "https://postqueen.ai/channels/slack.md"
last_updated: "2026-09-25"
llms_txt: "https://postqueen.ai/llms.txt"
---

# Schedule Slack posts with your AI agent.

Slack message scheduler

Schedule messages and images to public and private Slack channels, under the name and picture you choose, with follow-ups as thread replies. Your AI agent can schedule them for you.

[Start 7-day trial for $0](https://app.postqueen.ai/auth?utm_source=postqueen.ai&utm_medium=landing&utm_campaign=trial&utm_content=channel-hero) [Limits and settings](https://postqueen.ai/channels/slack#limits) $0 due today. Cancel in one click.

What you can publish

## Post types on Slack.

- Supported Channel message Sent as Slack mrkdwn; long text is split into sections at line breaks
- Supported Images Shown under the text as image blocks
- Supported Thread replies Follow-ups reply in the thread, each with an optional delay
- Supported Custom name and picture The name and avatar you set for the channel in PostQueen
- Not supported File uploads and video Video is refused before scheduling, and files are not uploaded
- Not supported Several channels in one workspace One channel per workspace per post

Limits at a glance

## Slack limits.

|  |  |  |
| --- | --- | --- |
| Message text | Up to 150,000 characters, sent in sections of up to 3,000 | [Official docs](https://docs.slack.dev/reference/block-kit/blocks/section-block) |
| Blocks per message | At most 50 blocks, checked before scheduling: one per 3,000 characters of text plus one per image | [Official docs](https://docs.slack.dev/reference/block-kit/blocks) |
| Image format | PNG, JPG or GIF; video is refused before scheduling | [Official docs](https://docs.slack.dev/reference/block-kit/blocks/image-block) |
| Posting rate | About 1 message per second per channel | [Official docs](https://docs.slack.dev/reference/methods/chat.postMessage) |
| Private channels | Invite the PostQueen app to the channel first | [Official docs](https://docs.slack.dev/reference/methods/chat.postMessage) |

From each network’s documentation and PostQueen’s own checks.

## How to connect

1. Open Add Channel and pick Slack.
2. Install the PostQueen app to your workspace.
3. Invite the app to any private channel you want to post in.
4. In each post, pick the channel.

## Settings in PostQueen

**Channel**

The public or private channel to post in. Required.

**Reply delay**

Each thread reply can wait its own delay.

From your agent

## Post to Slack by asking.

Ask Grok Bot, Muse, Claude, ChatGPT or any AI agent, and the post lands on your calendar.

- [![Grok Bot](https://postqueen.ai/assets/agents/grok-bot.png)](https://postqueen.ai/grok-bot)
- [![Muse](https://postqueen.ai/assets/agents/muse.svg)](https://postqueen.ai/muse)
- [![OpenClaw](https://postqueen.ai/assets/agents/openclaw.png)](https://postqueen.ai/openclaw)
- [![Hermes Agent](https://postqueen.ai/assets/agents/hermes-agent.png)](https://postqueen.ai/hermes-agent)
- [![Claude](https://postqueen.ai/assets/agents/claude.svg)](https://postqueen.ai/claude)
- [![ChatGPT](https://postqueen.ai/assets/agents/chatgpt.png)](https://postqueen.ai/chatgpt)
- [![Grok](https://postqueen.ai/assets/agents/grok.svg)](https://postqueen.ai/grok)
- [![Claude Code](https://postqueen.ai/assets/agents/claude-code.svg)](https://postqueen.ai/claude-code)
- [![Codex](https://postqueen.ai/assets/agents/codex.svg)](https://postqueen.ai/codex)
- [![Cursor](https://postqueen.ai/assets/agents/cursor.png)](https://postqueen.ai/cursor)
- [![Gemini CLI](https://postqueen.ai/assets/agents/gemini-cli.png)](https://postqueen.ai/gemini-cli)

[Post from your agent](https://postqueen.ai/mcp)

## Good to know

- Long messages are split into sections at line breaks, up to 150,000 characters.
- Invite the PostQueen app to private channels before you schedule to them.
- Each post links to the message in Slack once it is sent.

## Slack questions, answered.

Anything else? Write to [support@postqueen.ai](mailto:support@postqueen.ai) and a person answers.

### Can I post to private Slack channels?

Yes. Invite the PostQueen app to the private channel first, then pick it in the post. Public channels work right after you install the app.

### Can I upload files or video to Slack?

No. Images are shown under the message as image blocks, but files are not uploaded, and a post with video is refused before it is scheduled.

### Whose name appears on the message?

The name and picture you set for the Slack channel in PostQueen, so a scheduled message can carry your brand or a team name.

### Can my AI agent post to Slack?

Yes. Connect PostQueen to your AI agent through the MCP server or the CLI and ask it for a message with images and thread replies in a channel of your connected workspace.

### Can I save a Slack post as a draft?

Yes. Save it as a draft from Create Post, or ask your AI agent to create a draft instead of scheduling it. Drafts wait on your PostQueen calendar, and length and required settings are checked only when you schedule the post.

## Similar networks

- [Discord](https://postqueen.ai/channels/discord)
- [Whop](https://postqueen.ai/channels/whop)
- [Listmonk](https://postqueen.ai/channels/listmonk)
- [LinkedIn](https://postqueen.ai/channels/linkedin)

[All 30+ networks](https://postqueen.ai/channels)

### Put Slack on autopilot, your way.

Schedule from the calendar or ask your agent. Every post lands on the calendar first.

[Start 7-day trial for $0](https://app.postqueen.ai/auth?utm_source=postqueen.ai&utm_medium=landing&utm_campaign=trial&utm_content=band-channel) $0 due today. Cancel in one click.