n8n Workflow: Post-Appointment Review Requests (Email & SMS)

Automate Post-Appointment Reviews with Email—and optional SMS

This n8n workflow automatically sends post-appointment review requests via SMTP email and (optionally) SMS using an HTTP API—while using Google Sheets to prevent duplicates, enforce cooldowns, and respect SMS STOP and email unsubscribe opt-outs.

What this workflow does

• Receives completed appointments via a webhook protected with header authentication (or runs on an optional 15-minute schedule to read completed appointments from a Google Sheets tab).
• Validates and normalizes appointment data, immediately returns a 202 response to the booking system, then waits your configured delay before messaging.
• Checks Google Sheets rules by loading Review_Log and Opt_Outs to skip duplicates, honor opt-outs, and enforce a cooldown between review requests.
• Sends a review request email through SMTP.
• Optionally sends an SMS via an HTTP request—only when enabled, within your configured send window, and consent rules are satisfied.
• Logs outcomes to Review_Log (sent, skipped, or failure) so the same contact isn’t asked twice.
• Captures opt-outs by recording inbound SMS STOP/START replies and email unsubscribe link clicks into Opt_Outs.

Use cases

• Reduce manual follow-ups for service bookings by sending review requests after each completed appointment.
• Launch a multi-channel review campaign (email + SMS) with guardrails to avoid over-messaging.
• Maintain compliance-friendly behavior by tracking opt-outs across both channels in Google Sheets.

Technical details

• n8n nodes/workflow logic: webhook, if, set, code, wait, switch
• Integrations: SMTP email, HTTP API (for SMS), Google Sheets (Review_Log, Opt_Outs, and optional Appointments tab)

Setup requirements

• Create a Google Sheet with tabs named Review_Log, Opt_Outs, and (if using schedule mode) Appointments, using the columns expected by the workflow.
• Add Google Sheets OAuth credentials and update the Google Sheet document ID in all Google Sheets nodes.
• Configure SMTP credentials for email delivery.