PostgreSQL Order Webhook Automation: Gmail & Slack Invoice Alerts

Automatically turn paid order webhooks into PostgreSQL orders, Slack alerts, and Gmail invoice/shipping emails

This n8n workflow receives payment webhook events, validates and stores orders in PostgreSQL, notifies your Slack warehouse team, generates PDF invoices with PDFMonkey, and emails customers with Gmail—including confirmation, shipping updates, and delayed delivery/review follow-ups.

What this workflow does

• Receives a POST webhook for a paid order and validates required fields (order ID, amount, and customer email) for correct formatting.
• Normalizes and stores order data by inserting the order into a PostgreSQL orders table and writing the payment event to an order_logs table.
• Alerts the warehouse via Slack as soon as the paid order is recorded.
• Calculates invoice totals with an 18% tax, sends the invoice payload to PDFMonkey, then checks the document status after a brief wait.
• If the PDF is generated successfully, updates PostgreSQL with the invoice URL, logs the invoice event, and emails the customer an order confirmation with the invoice download link using Gmail.
• Creates shipping details (tracking ID, courier name, estimated delivery), updates the order as shipped in PostgreSQL, logs the shipment event, and emails a shipping notification to the customer via Gmail.
• After a 3-day delay, marks the order as delivered in PostgreSQL, logs delivery, emails a delivery feedback request, waits 1 day, then emails a product review request.
• Generates a reward coupon code and sends the discount to the customer (as part of post-delivery follow-ups).
• Posts daily sales metrics to Slack.

Use cases

• Turn payment confirmations into instant order capture in PostgreSQL with Slack team visibility.
• Send customers automated invoice, shipping, delivery feedback, and review emails—without manual coordination.
• Maintain auditable order history using order_logs for each lifecycle stage.

Technical details

• Nodes/activities: webhook, if, set, wait, Gmail, Slack
• Integrations: PostgreSQL for orders + order_logs, PDFMonkey for PDF invoice generation, Gmail for customer emails, Slack for warehouse alerts and daily sales metrics