Draft and approve Gmail replies with OpenAI and CustomJS

Quick Overview This workflow drafts replies for unread Gmail messages using OpenAI, publishes a Tailwind/Alpine approval dashboard to CustomJS, and sends approved replies back through Gmail via a webhook submission.

How it works 1. Starts manually and pulls unread emails from Gmail (up to the configured limit). 2. Filters out messages whose sender contains common no-reply patterns. 3. Sends each remaining email’s subject, snippet, sender, and recipient to OpenAI (gpt-5) to generate a draft reply. 4. Combines the email metadata with the generated drafts and builds a single HTML inbox-style approval page that posts approvals back to an n8n webhook. 5. Uploads (upserts) the generated HTML dashboard to CustomJS as a hosted page. 6. Receives approved/edited reply text via the webhook, replies to the original message in Gmail using the message ID, and then marks the message as read.

Setup 1. Add a Gmail OAuth2 credential and select it for the Gmail read, reply, and mark-as-read steps. 2. Add an OpenAI API credential and ensure the selected model (gpt-5) is available in your OpenAI account. 3. Add a CustomJS credential and set the target page name you want to upsert (for example, “Dashboard”). 4. In the HTML builder code, set N8NBASEURL to your reachable n8n URL and switch the webhook prefix from webhook-test to webhook for production. 5. Activate the workflow so the “email-reply-submit” webhook endpoint can receive approvals from the hosted dashboard.