# Check supplier invoices from Gmail with OpenAI: n8n workflow

> Started by an arriving email, and works across Gmail, Google Sheets and Slack. It hands the judgement calls to OpenAI.

Source: https://millionrounds.com/workflow/check-supplier-invoices-from-gmail-with-openai (Millionrounds; every figure on the page links to its filing or article)

[Automation library](https://millionrounds.com/workflows) · [Money admin](https://millionrounds.com/workflows?category=Money+admin#library)

# Check supplier invoices from Gmail with OpenAI

Started by an arriving email, and works across Gmail, Google Sheets and Slack. It hands the judgement calls to OpenAI. 17 steps, 2 branches: a working afternoon to understand properly.

Medium Calls a model: OpenAI

[Download free](https://millionrounds.com/login?next=%2Fapp%2Fworkflow%2Fcheck-supplier-invoices-from-gmail-with-openai)

**17 steps** Medium: a working afternoon

**2** Branches: places the flow splits

**0** Loops or waits

**3** Services it connects to

## The flow

Starts it 2 Model 2 Logic 4 Service 9

The steps in the order they run, from what starts it.

- 1 **Invoice arrives by email** Gmail trigger *Starts it*
- 2 **Extraction model** Lm Chat Open Ai *Model*
- 3 **If the run breaks** Error trigger *Starts it*
- 4 **Keep only PDF attachments** Filter *Logic*
- 5 **Pull the invoice fields** Information Extractor *Model*
- 6 **Alert finance that it broke** Slack *Service*
- 7 **Read the PDF** Extract From File *Service*
- 8 **Supplier master** Google Sheets *Service*
- 9 **Open purchase orders** Google Sheets *Service*
- 10 **Invoices already posted** Google Sheets *Service*
- 11 **Run the checks** Code *Logic*
- 12 **Did every check pass?** If *Logic*
- 13 **Inside the approval limit?** If *Logic*
- 14 **Park it in the exceptions queue** Google Sheets *Service*
- 15 **Post it to the ledger** Google Sheets *Service*
- 16 **Ask a human to sign it off** Slack *Service*
- 17 **Tell the supplier what is wrong** Gmail *Service*

## How it's built

- **Starts on:** An arriving email
- **Steps:** 17, with 2 branches
- **Size:** Medium: a working afternoon
- **Connects to:** Gmail, Google Sheets, Slack
- **Model:** OpenAI

## Questions

What does it need to run?

An n8n account, plus your own Gmail, Google Sheets and Slack accounts, and a key for OpenAI. You connect your own accounts after importing it; none are included.

What starts it?

It starts on an arriving email.

Does it use AI?

Yes. It calls OpenAI. Model calls are billed by the provider, not by n8n.

How long does it take to set up?

Plan an afternoon. 17 steps is enough that you should read each one before running it.

How do I import it?

Copy the workflow, open a new workflow in n8n and paste. The steps appear on the canvas, ready for your own accounts.

**Before you run it**

Nothing here has been tested by us. It is somebody's working automation, read and described from its own steps. Treat the connections it wants as a list of accounts it will touch, and read the 17 steps before you point it at anything that matters.

## Run it in n8n

- **Create your n8n account** Free to start. n8n is where the workflow runs. [Create an n8n account ↗](https://millionrounds.com/n8n)
- **Download the workflow** Free with a Millionrounds account. [Download free](https://millionrounds.com/login?next=%2Fapp%2Fworkflow%2Fcheck-supplier-invoices-from-gmail-with-openai)
- **Paste it into n8n** Open a new workflow in n8n and paste. Then connect your own accounts.

Stored with the author's traces removed: canvas notes, instance identifiers, saved credential names and any live document they had left behind.

## Connects to

Each opens the other workflows that use it.

[Gmail](https://millionrounds.com/workflows?service=Gmail#library)[Google Sheets](https://millionrounds.com/workflows?service=Google+Sheets#library)[Slack](https://millionrounds.com/workflows?service=Slack#library)

## Workflows like it

Also money admin, with the same services where possible, closest in size first.

- [**AI invoice and receipt data extractor with OpenAI** 17 steps · calls a model · Google Sheets](https://millionrounds.com/workflow/ai-invoice-and-receipt-data-extractor-with-openai)
- [**Auto expense tracker from LINE messages with OpenAI** 17 steps · calls a model · Google Sheets](https://millionrounds.com/workflow/auto-expense-tracker-from-line-messages-with-openai)
- [**Auto-extract & approve invoices with OpenAI and Jotform** 17 steps · calls a model · Gmail, Google Sheets](https://millionrounds.com/workflow/auto-extract-and-approve-invoices-with-openai-and-jotform)
- [**Automate tax compliance validation with OpenAI** 17 steps · calls a model · Gmail](https://millionrounds.com/workflow/automate-tax-compliance-validation-with-openai)
- [**Automated invoice data extraction with LlamaParse and Gemini** 17 steps · calls a model · Gmail, Google Sheets](https://millionrounds.com/workflow/automated-invoice-data-extraction-with-llamaparse-and-gemini)
- [**Automatic email invoice archiving & data extraction with Gmail** 17 steps · calls a model · FTP, Gmail](https://millionrounds.com/workflow/automatic-email-invoice-archiving-and-data-extraction-with-g)