{"product_id":"automate-overdue-invoice-follow-ups-openai-gmail-sheets","title":"Automate Overdue Invoice Follow-Ups: OpenAI + Gmail + Sheets","description":"\u003ch3\u003eAutomate overdue invoice follow-ups using OpenAI, Gmail, and Google Sheets\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow checks your \u003cstrong\u003eInvoices\u003c\/strong\u003e Google Sheet every morning, reviews each \u003cstrong\u003eoverdue\u003c\/strong\u003e client thread in \u003cstrong\u003eGmail\u003c\/strong\u003e, and uses \u003cstrong\u003eOpenAI\u003c\/strong\u003e to decide whether to send the next stage reminder—defer it—or route it for \u003cstrong\u003ehuman review\u003c\/strong\u003e. The chosen action is then written back to Google Sheets so nothing falls through the cracks.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRuns daily at 9:00 AM (America\/Chicago)\u003c\/strong\u003e and reads the \u003cstrong\u003eInvoices\u003c\/strong\u003e tab in Google Sheets.\u003c\/li\u003e\n  \u003cli\u003eSelects only \u003cstrong\u003eeligible\u003c\/strong\u003e invoices (not paid\/void\/closed, not on manual hold, not already in human review, and overdue long enough for the next reminder stage).\u003c\/li\u003e\n  \u003cli\u003eFor each eligible invoice, searches \u003cstrong\u003eGmail\u003c\/strong\u003e for recent correspondence with the client and builds a compact thread history (including dedupe checks for an exact stage subject and detection of recent activity within the configured window).\u003c\/li\u003e\n  \u003cli\u003eIf the exact stage email subject already exists, it updates the sheet as already reminded.\u003c\/li\u003e\n  \u003cli\u003eIf there was recent conversation, it \u003cstrong\u003edefers\u003c\/strong\u003e the next follow-up and records the decision.\u003c\/li\u003e\n  \u003cli\u003eOtherwise, it sends the thread history to \u003cstrong\u003eOpenAI\u003c\/strong\u003e to classify the context as \u003cstrong\u003eSEND\u003c\/strong\u003e, \u003cstrong\u003eDEFER\u003c\/strong\u003e, or \u003cstrong\u003eHUMAN\u003c\/strong\u003e, then safely parses\/validates the JSON with a confidence threshold.\u003c\/li\u003e\n  \u003cli\u003eIf \u003cstrong\u003eSEND\u003c\/strong\u003e, it generates and sends a deterministic stage-based reminder email via Gmail and writes the sent stage + next follow-up date back to Google Sheets.\u003c\/li\u003e\n  \u003cli\u003eIf \u003cstrong\u003eDEFER\u003c\/strong\u003e or \u003cstrong\u003eHUMAN\u003c\/strong\u003e, it updates Google Sheets accordingly for later handling.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eSaaS operations teams that need reliable \u003cstrong\u003eoverdue invoice chasing\u003c\/strong\u003e without manual checking.\u003c\/li\u003e\n  \u003cli\u003eAutomation engineers building an \u003cstrong\u003eAI-assisted email follow-up\u003c\/strong\u003e pipeline with audit-friendly state in Sheets.\u003c\/li\u003e\n  \u003cli\u003eBusinesses that want to avoid duplicate reminders and intelligently pause when clients respond.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations\/nodes:\u003c\/strong\u003e Gmail, Google Sheets, OpenAI\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003en8n components:\u003c\/strong\u003e if, code, no op, sticky note (used to control logic, parsing\/validation, and workflow readability)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCore features:\u003c\/strong\u003e stage-based deduping, recent-activity deferral, JSON parsing with confidence threshold, and decision logging back to Google Sheets\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":45967645704371,"sku":"N8N-19245","price":42.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/b8_-tOrAMmFOSpkllOoyT_84FhwFMf.png?v=1788686195","url":"https:\/\/buyflowscripts.com\/products\/automate-overdue-invoice-follow-ups-openai-gmail-sheets","provider":"N8N Commerce","version":"1.0","type":"link"}