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Mattermost (plugin)

Status: supported via plugin (bot token + WebSocket events). Channels, groups, and DMs are supported. Mattermost is a self-hostable team messaging platform; see the official site at mattermost.com for product details and downloads.

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Plugin required

Mattermost ships as a plugin and is not bundled with the core install. Install via CLI (npm registry): 
openclaw plugins install @openclaw/mattermost
Local checkout (when running from a git repo): 
openclaw plugins install ./extensions/mattermost
If you choose Mattermost during configure/onboarding and a git checkout is detected, OpenClaw will offer the local install path automatically. Details: Plugins

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Quick setup

  1. Install the Mattermost plugin.
  2. Create a Mattermost bot account and copy the bot token.
  3. Copy the Mattermost base URL (e.g., https://chat.example.com).
  4. Configure OpenClaw and start the gateway.
Minimal config: 
{
  channels: {
    mattermost: {
      enabled: true,
      botToken: "mm-token",
      baseUrl: "https://chat.example.com",
      dmPolicy: "pairing",
    },
  },
}

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Native slash commands

Native slash commands are opt-in. When enabled, OpenClaw registers oc_* slash commands via the Mattermost API and receives callback POSTs on the gateway HTTP server. 
{
  channels: {
    mattermost: {
      commands: {
        native: true,
        nativeSkills: true,
        callbackPath: "/api/channels/mattermost/command",
        // Use when Mattermost cannot reach the gateway directly (reverse proxy/public URL).
        callbackUrl: "https://gateway.example.com/api/channels/mattermost/command",
      },
    },
  },
}
Notes:
  • native: "auto" defaults to disabled for Mattermost. Set native: true to enable.
  • If callbackUrl is omitted, OpenClaw derives one from gateway host/port + callbackPath.
  • For multi-account setups, commands can be set at the top level or under channels.mattermost.accounts.<id>.commands (account values override top-level fields).
  • Command callbacks are validated with per-command tokens and fail closed when token checks fail.
  • Reachability requirement: the callback endpoint must be reachable from the Mattermost server.
    • Do not set callbackUrl to localhost unless Mattermost runs on the same host/network namespace as OpenClaw.
    • Do not set callbackUrl to your Mattermost base URL unless that URL reverse-proxies /api/channels/mattermost/command to OpenClaw.
    • A quick check is curl https://<gateway-host>/api/channels/mattermost/command; a GET should return 405 Method Not Allowed from OpenClaw, not 404.
  • Mattermost egress allowlist requirement:
    • If your callback targets private/tailnet/internal addresses, set Mattermost ServiceSettings.AllowedUntrustedInternalConnections to include the callback host/domain.
    • Use host/domain entries, not full URLs.
      • Good: gateway.tailnet-name.ts.net
      • Bad: https://gateway.tailnet-name.ts.net

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Environment variables (default account)

Set these on the gateway host if you prefer env vars:
  • MATTERMOST_BOT_TOKEN=...
  • MATTERMOST_URL=https://chat.example.com
Env vars apply only to the default account (default). Other accounts must use config values.

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Chat modes

Mattermost responds to DMs automatically. Channel behavior is controlled by chatmode:
  • oncall (default): respond only when @mentioned in channels.
  • onmessage: respond to every channel message.
  • onchar: respond when a message starts with a trigger prefix.
Config example: 
{
  channels: {
    mattermost: {
      chatmode: "onchar",
      oncharPrefixes: [">", "!"],
    },
  },
}
Notes:
  • onchar still responds to explicit @mentions.
  • channels.mattermost.requireMention is honored for legacy configs but chatmode is preferred.

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Access control (DMs)

  • Default: channels.mattermost.dmPolicy = "pairing" (unknown senders get a pairing code).
  • Approve via:
    • openclaw pairing list mattermost
    • openclaw pairing approve mattermost <CODE>
  • Public DMs: channels.mattermost.dmPolicy="open" plus channels.mattermost.allowFrom=["*"].

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Channels (groups)

  • Default: channels.mattermost.groupPolicy = "allowlist" (mention-gated).
  • Allowlist senders with channels.mattermost.groupAllowFrom (user IDs recommended).
  • @username matching is mutable and only enabled when channels.mattermost.dangerouslyAllowNameMatching: true.
  • Open channels: channels.mattermost.groupPolicy="open" (mention-gated).
  • Runtime note: if channels.mattermost is completely missing, runtime falls back to groupPolicy="allowlist" for group checks (even if channels.defaults.groupPolicy is set).

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Targets for outbound delivery

Use these target formats with openclaw message send or cron/webhooks:
  • channel:<id> for a channel
  • user:<id> for a DM
  • @username for a DM (resolved via the Mattermost API)
Bare IDs are treated as channels.

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Reactions (message tool)

  • Use message action=react with channel=mattermost.
  • messageId is the Mattermost post id.
  • emoji accepts names like thumbsup or :+1: (colons are optional).
  • Set remove=true (boolean) to remove a reaction.
  • Reaction add/remove events are forwarded as system events to the routed agent session.
Examples: 
message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup
message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup remove=true
Config:
  • channels.mattermost.actions.reactions: enable/disable reaction actions (default true).
  • Per-account override: channels.mattermost.accounts.<id>.actions.reactions.

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Multi-account

Mattermost supports multiple accounts under channels.mattermost.accounts: 
{
  channels: {
    mattermost: {
      accounts: {
        default: { name: "Primary", botToken: "mm-token", baseUrl: "https://chat.example.com" },
        alerts: { name: "Alerts", botToken: "mm-token-2", baseUrl: "https://alerts.example.com" },
      },
    },
  },
}

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Troubleshooting

  • No replies in channels: ensure the bot is in the channel and mention it (oncall), use a trigger prefix (onchar), or set chatmode: "onmessage".
  • Auth errors: check the bot token, base URL, and whether the account is enabled.
  • Multi-account issues: env vars only apply to the default account.