Ping Slack when a lead who already said yes writes back

When a prospect who is already labeled Interested or Meeting request sends another message, Master Inbox posts it to Slack, because second replies are often the buying signal.

Alerts

SlackRepSDR managerTeam plan

When

Incoming MessageAll channels

Only if

Label is Interested, Meeting request or Follow up

Then

Notify in SlackPost the new message, prospect and thread link to the owner's channel

Why teams run it

Follow-up questions from warm leads get answered fast instead of hiding behind the first alert.

Set it up in Master Inbox

In Master Inbox, open Settings, then Workflows, and click Add a workflow.
Name it Ping Slack when a lead who already said yes writes back.
Set the trigger to Incoming Message and choose All channels.
Add a condition: Label is Interested, Meeting request or Follow up.
Add the action Notify in Slack: Post the new message, prospect and thread link to the owner's channel.
Save the workflow and switch it to Active.

Before you start, connect Slack under Settings, Integrations.

Or create it with the API

Everything in the workflow builder is also in the Master Inbox API. This request creates the same workflow. Replace the example ids with your own label, list and campaign ids from GET /workflows/filter-fields. This workflow also uses conditions: add them under trigger_config.conditions, as shown on the conditions page.

curl -X POST https://api.masterinbox.com/api/api-webhook/v1/api/workflows/create-workflow \
  -H "Authorization: Bearer $MASTER_INBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "name": "Ping Slack when a lead who already said yes writes back",
  "trigger_type": "incoming_message",
  "trigger_config": {
    "channel_ids": [
      "-1"
    ]
  },
  "action_configs": [
    {
      "action_type": "slack_notify",
      "payload_variables": [
        "name",
        "company_name",
        "label_names",
        "text",
        "thread_url"
      ],
      "show_draft": true
    }
  ]
}'

Full reference: workflow API guide and API docs.

Or ask Claude, ChatGPT or Grok to build it

Our workflow guide is written for AI agents to read. Give your assistant your API key and this prompt:

Read https://app.masterinbox.com/public-workflow-api.md and use my Master Inbox API key to create this workflow: "Ping Slack when a lead who already said yes writes back". First call GET /workflows/filter-fields and look up my label, list and channel ids, then create the workflow and tell me what you set up.

Questions

Why not use the Add Label trigger?

The label is already on the thread, so it does not change. Incoming Message fires on every new reply and the label condition keeps it to warm leads.

Does it fire on the very first reply too?

Only if the label is already set when the condition is checked. Keep your first-reply alert on the Add Label trigger.

Can I build this workflow through the API?

Yes. Send the create-workflow request shown on this page with your Master Inbox API key. The API checks the payload first and lists every problem by field if anything is off.

Which plan includes this?

This workflow works on the Team plan. Every plan has unlimited users and starts with a free 7-day POC.