Check, register and remind on supplier e-invoices with Gmail, invoapi, Google Drive, Sheets and Anthropic

Quick overview

This workflow monitors a Gmail inbox for incoming XML or PDF invoice attachments, validates each file with invoapi against e-invoice rules, saves valid invoices to Google Drive, replies to suppliers with validation errors, and forwards non-e-invoices or failed checks to accounting for manual review.

How it works

1. Triggers every minute when a new Gmail email arrives that has an XML or PDF attachment.
2. Extracts only XML and PDF attachments and creates one workflow item per attachment while carrying over the email metadata needed for follow-up.
3. Sends each attachment to invoapi to validate it as an EN 16931/XRechnung-compatible e-invoice and returns a validation report.
4. Uploads invoices marked as valid to the configured Google Drive accounting folder.
5. For invoices marked as invalid, composes a readable error list from the invoapi report and replies to the supplier in the original Gmail thread.
6. For attachments that are not detected as e-invoices or where validation fails, forwards a review request email to the configured accounting address.

Setup

1. Install and configure the invoapi community node (n8n-nodes-invoapi) and add an invoapi API credential.
2. Add Gmail credentials for the inbox to monitor and to send replies/forwards.
3. Add Google Drive credentials and set the target Drive folder ID in the workflow configuration.
4. Update the review/forwarding email address in the workflow configuration and adjust the Gmail search query if you want to limit which emails are processed.