# n8n + Signatoro FAQ: AI Gmail Drafts With a Real Signature > How the n8n Signatoro workflow works: Gmail Trigger with Simplify off, the OpenAI prompt, the signature HTTP Request, the key error and the draft. Source: https://learn.ynteractive.com/content/blog/n8n-signatoro-signed-reply-faq · Updated 2026-10-20 · Free from Stepthrough (https://learn.ynteractive.com) Quick answer The n8n Signatoro workflow has four nodes: a **Gmail Trigger** starts it when a new email lands, **OpenAI** writes a warm reply with no name or signature, an **HTTP Request** node fetches the sender's real signature from Signatoro at `https://signatoro.com/api/v1/signature`, and **Gmail** saves the reply plus the signature as a draft in the same thread. A person reads it and clicks Send. The free [n8n Signatoro signed reply lesson](https://learn.ynteractive.com/content/n8n-signatoro-ai-email-reply-signature) builds it on real screens from 20 October 2026. Last updated October 20, 2026 [Take the free module →](https://learn.ynteractive.com/courses/n8n-jump-start/19)Module 19 of the free [n8n Jump Start](https://learn.ynteractive.com/courses/n8n-jump-start) course, about 10 minutes. No account needed. By [Robert Breen](https://learn.ynteractive.com/content/about) · Published October 20, 2026 · Updated October 20, 2026 · 4 min read Signatoro · n8n · FAQ · Gmail · Email What the lesson actually ran: the trigger used a pinned sample email from Daniel Brooks (made up), and the [OpenAI](https://learn.ynteractive.com/content/glossary#openai) step ran for real on the OpenAI credential that came with the [n8n Cloud](https://learn.ynteractive.com/content/glossary#n8n-cloud) account. The Signatoro call used a placeholder key, so it shows Signatoro's own **missing_api_key** answer. No key was created and no draft was saved. The practice, Brookside Dental, and its patient coordinator, Dana Whitfield, are made up. ## What does each node do? | Node | Name on the canvas | What it does | | --- | --- | --- | | [Gmail Trigger](https://learn.ynteractive.com/content/glossary/gmail-trigger) | **New patient email** | Checks the inbox every minute | | OpenAI | **Write the reply** | Writes the reply, ending with a closing line and no name | | HTTP Request | **Get signature (Signatoro)** | Returns Dana's signature as HTML | | Gmail | **Save draft reply** | Saves a draft in the patient's thread | ## How is the Signatoro request set up? In **Get signature (Signatoro)**, **Method** is **GET** and **URL** is `https://signatoro.com/api/v1/signature`. **Authentication** is **Generic Credential Type** and **Generic Auth Type** is **Bearer Auth**, because Signatoro reads the key from an **Authorization: Bearer** header. The lesson's credential is named **Signatoro - add your key**: click the pencil, paste your key into **Bearer Token** and click **Save**. Signatoro answers with **html**, **text** and **sender**. The [HTTP Request node](https://learn.ynteractive.com/content/glossary#http-request-node) entry covers the basics. ## How does the draft come together? **Save draft reply** is a Gmail node with **Resource: Draft** and **Operation: Create**. **Subject** is **Re:** plus the email's subject. **Email Type** is **HTML**. **Message** is the AI's reply followed by `{{ $json.html }}`, the signature from Signatoro. Under **Options**, **Thread ID** puts the draft in the patient's own thread and **To Email** is the sender's address, both taken from the trigger. Reply first, signature second: the lesson calls that order the whole trick. ## What did the AI write in the test? GPT-5 mini answered Daniel's made-up email in short HTML paragraphs. It greeted him by name, thanked him for asking about Emma's first checkup, said the practice would call within one business day to book a time, and ended with "Kind regards," and no name. That ending is on purpose: Signatoro signs, the AI doesn't. ## Try it free, step by step **n8n + Signatoro: AI Drafts Every Reply, Signatoro Signs It**. Stop leaving client emails waiting. A Gmail Trigger starts it, OpenAI writes a personal reply, one HTTP Request node fetches the sender's real signature from Signatoro, and Gmail saves a draft reply… You do every step yourself in a practice copy of n8n, it checks your work as you go, and “Do it for me” finishes any step you get stuck on. Free, and nothing touches your real accounts. [Start the free lesson](https://learn.ynteractive.com/modules/n8n-signatoro-signed-reply) [Or read the full step-by-step guide](https://learn.ynteractive.com/content/n8n-signatoro-ai-email-reply-signature) ## Frequently asked questions **Where do I get the Signatoro API key?** On signatoro.com, save your signature first: fill in **Your details** and click **Save signature**. Then scroll to **For tools and assistants** and click **Generate API key**. Copy it straight away: it's shown once. The example request under the button is what n8n sends. **Where does the key go in n8n?** Only in the Bearer Auth [credential](https://learn.ynteractive.com/content/glossary#credential), in **Bearer Token**. n8n stores it encrypted and adds it to every request, so it never shows in the workflow, the prompt or an exported file. If it leaks, make a new key on Signatoro. **Why does the test run say Authorization failed?** The lesson used a placeholder key, so Signatoro answered **Authorization failed** with **missing_api_key**. A wrong key gives **invalid_api_key**. Either way, n8n reached Signatoro. Paste your real key and the node returns the signature. **Why turn Simplify off in the Gmail Trigger?** The full email has **text**, **subject**, **threadId** and the sender's address, and the next nodes need all of them. The [Gmail Trigger](https://learn.ynteractive.com/content/glossary/gmail-trigger) entry explains polling and Simplify. **How fast does a draft appear?** **Poll Times** is **Every Minute**, so a draft is ready about a minute after the email lands. **Why doesn't the AI sign the reply?** A model asked to sign with a name and phone number can get them wrong, and a hard-coded name goes stale when someone changes role. Fetching the signature on every run means a change on Signatoro reaches the next email. **Can I get a shorter signature?** Yes. Add `?mode=short` to the URL for a shorter one: name, role and one link. **Do I need my own OpenAI key?** Not to start. The lesson's OpenAI node used the OpenAI credential that came with the n8n Cloud account. You can connect your own key instead. **What does each draft use on Signatoro?** Each draft is one API request. Check Signatoro's own docs for its API usage terms before you rely on it for a busy inbox. **Can it send the reply automatically?** Start with drafts. A person reading every reply is what makes an AI reply safe to use with clients, which is the idea behind [human in the loop](https://learn.ynteractive.com/content/glossary/human-in-the-loop). **Is there a Make or Zapier version?** Yes, with the same practice and prompt rules: [the Make lesson](https://learn.ynteractive.com/modules/make-add-ai) and [the Zapier lesson](https://learn.ynteractive.com/modules/zapier-ai-reply). The [Signatoro email signature FAQ](https://learn.ynteractive.com/content/blog/signatoro-email-signature-faq) covers both. ## Key takeaways - Four nodes: Gmail Trigger, OpenAI, one GET request to Signatoro, Gmail draft. - The Signatoro key lives in a Bearer Auth credential only. - **missing_api_key** in the test means only the key is missing. - The AI ends with a closing line. Signatoro adds the signature after it. - Save drafts in the same thread and let a person click Send. For setup errors, read [the n8n Signatoro signed reply mistakes](https://learn.ynteractive.com/content/blog/n8n-signatoro-signed-reply-mistakes), browse the [cheat sheets](https://learn.ynteractive.com/content/cheat-sheets), or [start the lesson](https://learn.ynteractive.com/modules/n8n-signatoro-signed-reply). ## Free lessons in this post - [n8n + Signatoro: AI Drafts Every Reply, Signatoro Signs It](https://learn.ynteractive.com/content/n8n-signatoro-ai-email-reply-signature): Stop leaving client emails waiting. A Gmail Trigger starts it, OpenAI writes a personal reply, one HTTP Request node fetches the sender's real signature from Signatoro… ## Watch it in a free lesson: Gmail AI Triage: Auto-Label Every Email and Draft Replies ### Gmail AI Triage: Auto-Label Every Email and Draft Replies: video walkthrough Full walkthrough · 2:31 · with captions Build an n8n workflow that reads each new email, sorts it as a lead, a client or an invoice with a Text Classifier, adds the matching Gmail label, and drafts a reply to clients for you to check. The whole lesson narrated step by step, recorded in Stepthrough’s simulated practice environment. [Watch it with chapters and the full transcript](https://learn.ynteractive.com/content/gmail-ai-triage-labels-drafts-n8n#watch) From the free lesson [Gmail AI Triage: Auto-Label Every Email and Draft Replies](https://learn.ynteractive.com/content/gmail-ai-triage-labels-drafts-n8n) ## Related terms Plain-English definitions, each with an example from a free lesson. [OpenAI](https://learn.ynteractive.com/content/glossary#openai) · [n8n Cloud](https://learn.ynteractive.com/content/glossary#n8n-cloud) · [Gmail Trigger](https://learn.ynteractive.com/content/glossary/gmail-trigger) [The full AI glossary](https://learn.ynteractive.com/content/glossary) ## Keep reading - [n8n + Signatoro AI Reply: 8 Mistakes and How to Fix Them](https://learn.ynteractive.com/content/blog/n8n-signatoro-signed-reply-mistakes): Fix the n8n Signatoro reply workflow: missing_api_key, a key in the prompt, Simplify left on, an AI that signs, drafts outside the thread and more. - [How to Automate Gmail Replies With AI Drafts (n8n)](https://learn.ynteractive.com/content/blog/ai-email-replies-gmail-drafts): How to automate Gmail replies with AI drafts: an n8n agent saves every reply as a draft in the same thread and never sends it. Five nodes, step by step. - [How to Connect Google Sheets and Gmail to n8n](https://learn.ynteractive.com/content/blog/connect-google-sheets-and-gmail-to-n8n): Connect Google Sheets to n8n step by step: Sign in with Google, the permission boxes, a separate Gmail credential, picking your sheet, and the usual snags. [All blog posts](https://learn.ynteractive.com/content/blog) · [All free tutorials](https://learn.ynteractive.com/content)