Draft AI follow-up email drafts for stale estimates with Claude and Google Sheets

Description

Quick overview
This workflow runs daily to read estimates from Google Sheets, identify stale items that need a follow-up, generate a personalized email draft with Anthropic Claude, save it as a Gmail draft, and update the source sheet with the latest follow-up date and status.

How it works
Runs daily on a schedule.
Loads all estimate rows from a Google Sheets document.
Filters for open/pending estimates where the last follow-up (or estimate date) is older than the configured threshold and a customer name and email are present.
Sends each stale estimate to the Anthropic Messages API (Claude) to generate a JSON follow-up email subject and body using the customer and estimate details.
Parses the JSON response and prepares the final email fields, falling back to a default message if parsing fails.
Creates a Gmail draft addressed to the customer using the generated subject and body.
Updates the matching row in Google Sheets to set the status to followup_drafted and record the new last_followup_date.

Setup
Create a Google Sheet (e.g. a tab named “Estimates”) with columns such as customer_name, customer_email, service_requested, estimate_amount, estimate_date, status, last_followup_date, and notes.
Add Google Sheets credentials in n8n and replace REPLACE_WITH_YOUR_SHEET_ID with your spreadsheet ID in both Google Sheets nodes.
Add an HTTP Header Auth credential for Anthropic (x-api-key) and attach it to the HTTP Request node, and ensure the anthropic-version header remains set.
Add Gmail credentials for creating drafts in your mailbox.
Update the configuration values (staleThresholdDays, businessName, senderName, and emailSignature) and adjust the scheduled run time as needed.