Sales teams miss chances when inboxes fill up. This setup listens for new replies from your email outreach and posts a clear alert in Slack. It also flags opt outs and marks warm leads so your team can act fast.

The flow starts when Lemlist detects a new reply. The text is cleaned from HTML into simple Markdown so the message looks tidy in Slack. An OpenAI model reads the reply and assigns one category such as Interested, Out of office, Unsubscribe, Not interested, or Other using a structured parser. The data is merged to keep the original content, the cleaned text, and the category together. A switch then routes the item: everyone gets a Slack block message, opt outs are unsubscribed in Lemlist, and Interested leads are marked as interested through the Lemlist API. The trigger is set to capture the first reply to avoid noise and focus on what matters.

You need a Lemlist API key, a Slack workspace with a channel for alerts, and an OpenAI API key. Pick your Slack channel, review the categories, and tune the switch rules to fit your playbook. Expect faster handoffs, fewer mistakes on unsubscribes, and cleaner data in Lemlist. Teams using outbound sequences, SDR groups, and agencies that manage client campaigns will see time savings and quicker follow up.

• On app event trigger fires when Lemlist receives a new reply and captures only the first response
• Markdown formatter converts HTML email content into clean text for Slack readability
• OpenAI Chat Model classifies replies into clear categories using a structured output parser
• Merge step keeps original data, cleaned text, and category in a single payload
• Switch node routes actions based on category for precise handling
• Slack block message posts a tidy alert with key fields to a chosen channel
• Lemlist Unsubscribe action removes leads who ask to opt out
• HTTP request marks interested leads directly in Lemlist for fast follow up

• Reduce manual inbox triage from 60 minutes a day to 5 minutes
• Automate 90% of reply routing with AI categorization
• Improve unsubscribe accuracy by up to 95% with automatic opt out handling
• Cut first response time on interested leads by up to 70% with instant Slack alerts
• Connect Lemlist, Slack and OpenAI in one flow for unified handoffs
• Handle up to 5 times more replies without adding headcount

1. Import the template into n8n: Create a new workflow in n8n > Click the three dots menu > Select 'Import from File' > Choose the downloaded JSON file.
2. You'll need accounts with Lemlist, Slack and OpenAI. See the Tools Required section above for links to create accounts with these services.
3. Open the Lemlist Trigger node. In the Credential to connect with dropdown, click Create new credential and paste your Lemlist API key from Settings > Integrations in your Lemlist account. Confirm the event is set to emailsReplied and the first reply option is enabled.
4. Open the Lemlist Unsubscribe node. Choose the same Lemlist credential. Leave the email and campaign fields mapped from the trigger so the correct lead is unsubscribed.
5. Open the Mark as interested HTTP Request node. In the credentials dropdown, select the Lemlist API credential so the POST request is authorized.
6. Open the OpenAI Chat Model node. Create a new OpenAI credential and add your API key from the OpenAI dashboard. Keep the model on gpt-4o unless you have a different plan.
7. Open the Structured Output Parser node and confirm the schema includes one field named category. No changes are required if it already matches.
8. Open the Categorize lemlist reply node. Review the prompt and categories and adjust wording if your team uses different labels.
9. Open the Slack node. Create a Slack credential by choosing Slack OAuth2 and follow the on screen steps. Set the Channel to the name where you want alerts and make sure the bot is invited to that channel.
10. Open the Switch node. Map categories to actions: Interested goes to Mark as interested, Unsubscribe goes to Unsubscribe, and all categories should also send to the Slack message branch.
11. Run a test by sending a reply to a test Lemlist campaign email. Confirm a Slack alert appears, check the lead status in Lemlist, and verify that opt outs are removed. If the alert fails, ensure the Slack bot is in the channel. If Lemlist calls fail, recheck your API key. If classification fails, confirm your OpenAI key and usage limits.