🧾 Classify invoice reminder replies with Claude Haiku, Gmail and Google Sheets
⚡ 1 views · 🧾 Invoice Processing
Description
Quick overview
This workflow monitors Gmail for replies to invoice reminders, uses Claude Haiku to classify each reply, logs the result to Google Sheets, and applies a matching Gmail label so you can quickly triage each one as payment made, promise to pay, dispute, question, unrelated, or needs review.
How it works
- Watch for invoice replies picks up new replies (default search: “invoice” in the subject, not sent by you).
- Clean reply strips quoted history and signatures.
- An AI model sorts the reply into Payment made, Promise to pay, Dispute, Question, Unrelated or Needs review, with any promised payment date (one week ahead if the customer gives none) and a one-line reason.
- Each reply is logged to Google Sheets, including a direct link back to the Gmail thread, and labelled in Gmail. Needs review is for replies a person should read: vague, mixed or sarcastic ones, or if the model fails (the error is logged).
Setup
- Credentials: connect Gmail, Google Sheets and your AI model (the Claude Haiku 5.5 node).
- Gmail labels: create six labels in Gmail: Payment made, Promise to pay, Dispute, Question, Unrelated and Needs review. Open each Label node and pick the label with the same name.
- Sheet: paste a blank Google Sheet’s URL, copied from the address bar, into Your settings. The header row is written on the first run.
- Update the Gmail search query to match how your invoice reminders are titled and filtered (for example, by subject keywords or sender).
Requirements
- Gmail and Google Sheets connected via Google OAuth (self-hosted n8n needs a Google Cloud app: https://docs.n8n.io/integrations/builtin/credentials/google/)
- An API key for Claude or another chat model
Customization
- Another model: swap the Claude Haiku 5.5 node for any chat model node (OpenAI, Gemini, Mistral, Ollama).
- Other classes: edit Classify reply, Reply class format and Route by class, then add a matching label.
Additional info
The workflow never sends email, so a tricky reply can at worst get a wrong label. It doesn’t check your invoices either: Payment made means the customer says they paid.
🔗 Nodes Used
Google Sheets, Gmail, Gmail Trigger, Basic LLM Chain, Anthropic Chat Model, Structured Output Parser
📥 Import
Download workflow.json and import into n8n:
Workflow menu → Import from File