How to Auto-Summarize Gmail Emails with AI Using n8n

Your inbox is full — important emails are buried, and you’re spending hours skimming threads just to find the ones that actually need your attention. What if every new email was automatically summarized by AI, pinged to your Slack, and logged to a spreadsheet — without you lifting a finger? In this tutorial, you’ll build exactly that using n8n, OpenAI, Slack, and Google Sheets. No code required, and it runs 24/7 in the background while you focus on work that matters.

Prefer to skip the setup? Grab the ready-made template → and be up and running in under 10 minutes.

What You’ll Build

1. A Gmail trigger polls your inbox every minute for new unread emails.
2. The email content is sent to OpenAI’s GPT-4o-mini model, which generates a crisp 2–3 sentence summary.
3. The summary is posted to a Slack channel (e.g., #email-digest) so you see it the moment it lands.
4. The email metadata and AI summary are simultaneously appended to a Google Sheets log — your permanent, searchable email archive.
5. You stay on top of every important email without ever opening your inbox to triage.

How It Works — The Big Picture

The workflow is a linear pipeline with one fan-out at the end. Gmail fires the trigger, two Set nodes shape the data, one HTTP Request calls OpenAI, and then both Slack and Google Sheets receive the result in parallel.

┌──────────────────────────────────────────────────────────────────────────┐
│  AUTO-SUMMARIZE GMAIL EMAILS WITH AI                                     │
│                                                                          │
│  [Gmail Trigger]                                                         │
│       │  new unread email detected                                       │
│       ▼                                                                  │
│  [Extract Email Fields]  ← pulls sender, subject, body text             │
│       │                                                                  │
│       ▼                                                                  │
│  [Summarize with OpenAI]  ← POST to GPT-4o-mini API                     │
│       │                                                                  │
│       ▼                                                                  │
│  [Prepare Notification Data]  ← merges summary + email metadata          │
│       │                                                                  │
│       ├──────────────────────────┐                                       │
│       ▼                          ▼                                       │
│  [Send Slack Notification]  [Log to Google Sheets]                       │
│   posts to #email-digest     appends row to "Email Log" sheet            │
└──────────────────────────────────────────────────────────────────────────┘

What You’ll Need

• n8n — self-hosted or n8n Cloud (free tier works)
• Gmail account — connected via Google OAuth2 in n8n
• OpenAI account — API key from platform.openai.com (GPT-4o-mini costs fractions of a cent per email)
• Slack workspace — with a channel like #email-digest and a Slack app connected in n8n
• Google Sheets — a new spreadsheet with a tab named Email Log

Estimated build time: 35–50 minutes from scratch, or under 10 minutes with the ready-made template.

Building the Workflow — Step by Step

1 Gmail Trigger (gmailTrigger)

This is the entry point. The Gmail Trigger node polls your inbox on a schedule and fires whenever it finds a new unread email. Think of it as a quiet watchdog that checks your mailbox every 60 seconds.

How to configure it:

1. In your n8n canvas, click + Add node and search for Gmail Trigger.
2. Connect your Google account when prompted (you’ll be redirected to Google’s OAuth screen).
3. Under Poll Times, set the interval to Every Minute — or adjust to every 5 minutes if you prefer less frequent checks.
4. Under Filters → Read Status, choose Unread so already-read emails don’t get processed again.
5. Leave Include Spam & Trash unchecked.

When this node fires, the output is a rich object containing the full email. Here’s what a sample output looks like:

{
  "id": "18e5a3b2c7d4e901",
  "subject": "Q2 Budget Review — Action Needed",
  "from": {
    "value": [{ "address": "sarah.thompson@acmecorp.com", "name": "Sarah Thompson" }]
  },
  "date": "2026-04-02T14:23:11.000Z",
  "text": "Hi James,\n\nI've attached the updated Q2 budget spreadsheet for your review..."
}

2 Extract Email Fields (Set)

The raw Gmail output has a lot of nested data. This Set node flattens it into clean, named fields that the rest of the workflow can reference easily.

How to configure it:

1. Add a Set node after Gmail Trigger and set mode to Manual Mapping.
2. Add the following fields using the expression editor:

3 Summarize with OpenAI (HTTP Request)

This is where the magic happens. You’ll make a direct API call to OpenAI’s Chat Completions endpoint using an HTTP Request node — transparent, flexible, and easy to customize.

How to configure it:

1. Add an HTTP Request node. Set Method to POST and URL to https://api.openai.com/v1/chat/completions.
2. Under Authentication, choose Generic Credential Type → HTTP Header Auth. Create a credential with Name: Authorization and Value: Bearer sk-YOUR_OPENAI_API_KEY.
3. Set Body Content Type to JSON and use this body:

{
  "model": "gpt-4o-mini",
  "messages": [
    {
      "role": "system",
      "content": "You are a concise email assistant. Summarize the following email in exactly 2-3 sentences."
    },
    {
      "role": "user",
      "content": "From: {{ $json.senderName }} <{{ $json.sender }}>\nSubject: {{ $json.subject }}\n\n{{ $json.bodyText }}"
    }
  ],
  "max_tokens": 200,
  "temperature": 0.2
}

4 Prepare Notification Data (Set)

After the OpenAI call, the email fields from Step 2 are no longer in scope. This second Set node reassembles everything — it grabs the AI summary and re-references the email metadata using n8n’s node-reference syntax.

5 Send Slack Notification (Slack)

This node posts the email summary to a Slack channel so your team sees it in real time. Connect your Slack workspace via OAuth, set the channel to #email-digest, and use this message text:

📧 *New Email Summary*
*From:* {{ $json.senderName }} <{{ $json.sender }}>
*Subject:* {{ $json.subject }}
*Received:* {{ $json.receivedAt }}

*AI Summary:*
{{ $json.summary }}

6 Log to Google Sheets (Google Sheets)

The final node appends a new row to your Email Log spreadsheet every time an email is processed — your permanent, searchable archive.

Set Operation to Append or Update Row, select your spreadsheet, set the sheet name to Email Log, and map these columns:

The Data Structure (Google Sheets)

Your Email Log sheet must have these exact column headers in row 1. Column names are case-sensitive.

Full System Flow

┌─────────────────────────────────────────────────────────────────────────────────┐
│  FULL SYSTEM FLOW — Gmail AI Summarizer                                         │
│                                                                                 │
│  Gmail Inbox                                                                    │
│     │  (new unread email arrives)                                               │
│     ▼                                                                           │
│  [Gmail Trigger]  ──polls every 60s──►  raw email object (id, from, subject,   │
│                                          date, text)                            │
│     │                                                                           │
│     ▼                                                                           │
│  [Extract Email Fields]  ─────────────► { sender, senderName, subject,         │
│                                           bodyText (≤4000 chars), receivedAt,  │
│                                           messageId }                           │
│     │                                                                           │
│     ▼                                                                           │
│  [Summarize with OpenAI]                                                        │
│     POST https://api.openai.com/v1/chat/completions                             │
│     model: gpt-4o-mini  ──────────────► { choices[0].message.content: "..." }  │
│     │                                                                           │
│     ▼                                                                           │
│  [Prepare Notification Data]  ────────► { summary, sender, senderName,         │
│                                           subject, receivedAt, messageId }      │
│     │                                                                           │
│     ├───────────────────────────────────────────────┐                          │
│     ▼                                               ▼                           │
│  [Send Slack Notification]               [Log to Google Sheets]                 │
│   POST to #email-digest                   APPEND row to "Email Log" tab         │
│                                                                                 │
│  ✅ Done — email summarized, team notified, and permanently archived            │
└─────────────────────────────────────────────────────────────────────────────────┘

Testing Your Workflow

1. Send a test email to yourself from another account. Use a realistic subject and write 3–4 sentences of body text.
2. In the n8n canvas, click the Gmail Trigger node and press Fetch Test Event. Your test email should appear as the sample data.
3. Click Execute from here to run the rest of the workflow with that email.
4. Check your #email-digest Slack channel — the summary should appear within seconds.
5. Open your Google Sheets Email Log — a new row should be appended with all six columns filled.
6. Once confirmed, click Save then toggle the Active switch to start the live workflow.

Frequently Asked Questions

What’s Next?

• Auto-reply to routine emails: Add a second AI call that drafts a reply, then use Gmail’s “Create Draft” action so you can review and send with one click.
• Priority scoring: Add a second OpenAI call that rates each email 1–5 for urgency. Route high-priority emails to a dedicated #urgent-emails Slack channel.
• Weekly digest email: Pair this workflow with a scheduled trigger that reads your Google Sheets log every Friday and emails a formatted weekly summary to your team.
• Notion integration: Replace or supplement the Google Sheets node with a Notion node to create a card in your “Inbox” database for each processed email.