Small note: this is an updated implementation-focused share of the purchase order workflow, with more detail on Gmail attachment handling, approval thresholds, urgency logic, Sheets output, and Slack notifications.
Purchase orders often arrive as email attachments, but approval usually depends on more than the PO number.
Procurement needs the vendor, required date, line items, subtotal, shipping, tax, grand total, payment terms, and whether the delivery date is urgent.
If that all sits in Gmail until someone opens the PDF, the approval process starts late.
So I built an n8n workflow that watches Gmail for PO attachments, extracts the PO data, calculates approval level by amount, flags urgency by required date, logs everything to Google Sheets, and sends a Slack summary to procurement.
What it does
Gmail receives a PO email → n8n downloads the attachment → PDF Vector extracts purchase order fields → Code node calculates approval level and urgency → Google Sheets logs the PO → Slack notifies procurement
The workflow checks Gmail every minute and downloads attachments using the attachment_ binary prefix.
Good fit for:
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Procurement teams
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Finance departments
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Operations managers
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Small businesses approving vendor purchases from email
For sensitive vendor pricing, finance, or procurement data, I recommend self-hosted n8n so workflow executions and attachments stay under your own infrastructure.
What gets extracted
The PDF Vector node extracts flat fields from the PO attachment:
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PO number
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Order date
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Required date
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Vendor name
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Vendor address
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Vendor contact
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Vendor email
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Vendor phone
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Ship-to name
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Ship-to address
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Ship-to attention
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Bill-to name
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Bill-to address
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Line items list
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Line item count
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Subtotal
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Shipping cost
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Tax
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Grand total
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Payment terms
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Shipping method
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Notes
The line items list is stored as one text field for reliable Sheets output.
Example:
4 x Dell monitors @ 240.00 = 960.00; 2 x docking stations @ 180.00 = 360.00
Approval logic
The Code node assigns approval level based on grand total.
Current thresholds:
< $1,000 → Auto-Approve
$1,000 to $4,999 → Manager Approval
$5,000 to $24,999 → Director Approval
≥ $25,000 → VP/CFO Approval
This is routing logic, not final approval. You can add approval nodes, manual review, or an external procurement system after this step.
Urgency logic
The Code node compares the required date to today.
Current logic:
Required in 3 days or less → Urgent
Required in 7 days or less → High
Otherwise → Normal
This makes it easier to see which POs need attention before a delivery deadline is missed.
What lands in Slack
The procurement channel receives a summary like this:
📦 New Purchase Order Received
Tracking: PO-MA8K2F9
PO Number: PO-2026-0148
Vendor: Acme Office Supply
Line Items (2):
4 x Dell monitors @ 240.00 = 960.00; 2 x docking stations @ 180.00 = 360.00
Total: $1,462.00
Required By: 2026-05-12
Approval Required: Manager Approval
Urgency: High
What lands in Google Sheets
The workflow appends one row per purchase order.
Headers:
Tracking ID | PO Number | Vendor | Order Date | Required Date | Line Items | Subtotal | Shipping | Tax | Grand Total | Approval Level | Urgency | Status | Received Date
Example row:
PO-MA8K2F9 | PO-2026-0148 | Acme Office Supply | 2026-05-08 | 2026-05-12 | 2 | 1320 | 40 | 102 | 1462 | Manager Approval | High | Pending Approval | 2026-05-08
Setup
You’ll need:
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Gmail account where PO emails arrive
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Google Sheets spreadsheet for the PO tracker
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n8n instance
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PDF Vector account
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Gmail credential in n8n
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Google Sheets credential in n8n
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Slack credential in n8n
Download
Workflow JSON:
Full workflow collection:
Setup Guide
Step 1: Get your PDF Vector API key
Create an account at pdfvector.com.
The free tier includes 100 credits/month, enough to test with sample purchase orders.
Step 2: Create your Google Sheet
Create a Sheet with this header row:
Tracking ID | PO Number | Vendor | Order Date | Required Date | Line Items | Subtotal | Shipping | Tax | Grand Total | Approval Level | Urgency | Status | Received Date
Step 3: Import the workflow
In n8n:
Workflows → Import from File → select JSON
Step 4: Configure Gmail
Gmail Trigger
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Connect Gmail OAuth2
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Keep spam/trash excluded
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Add Gmail filters if needed
Example Gmail filter:
has:attachment subject:(purchase order OR PO)
Get a message
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Downloads attachments
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Uses the
attachment_prefix
Step 5: Configure PDF extraction
PDF Vector - Extract PO
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Add your PDF Vector credential
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Input type: file
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Binary property:
attachment_0 -
Keep the schema unless you need more fields
Step 6: Configure routing logic
Process PO
This Code node creates:
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tracking ID
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formatted grand total
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approval level
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urgency
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days until required date
Edit thresholds here if your procurement rules are different.
Step 7: Configure outputs
Log to PO Tracker
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Connect Google Sheets
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Select your spreadsheet
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Map the headers
Notify Procurement
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Connect Slack
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Select the procurement or finance channel
Step 8: Test with different PO amounts
Test with:
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one PO under $1,000
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one PO above $1,000
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one PO above $5,000
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one PO above $25,000
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one PO required within 3 days
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one PO required within 7 days
Accuracy
This workflow is usually strongest on:
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PO number
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Vendor name
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Order date
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Required date
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Grand total
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Payment terms
Fields that need more review:
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Complex line-item tables
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Multiple ship-to locations
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Split shipping charges
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Tax-exempt POs
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Handwritten or stamped notes
For procurement workflows, keep a human approval step before issuing payment or committing funds.
Cost
Structured extraction uses credits per page.
Simple estimate:
1-page PO ≈ 3 credits
100 free credits/month ≈ around 30 single-page POs for testing
Multi-page POs with long line-item tables will use more credits.
Customizing it
Change approval thresholds
Edit the Code node.
Example:
< $500 → Auto-Approve
$500-$2,499 → Manager
$2,500-$9,999 → Director
$10,000+ → CFO
Add approval buttons
Add Slack interactive approval or connect to your procurement system.
Add vendor validation
Look up vendor name in a Google Sheets vendor database before routing.
Add duplicate PO detection
Check whether the PO number already exists in the tracker before appending a new row.
Add exception routing
Route POs to a Needs Review tab when:
PO number is missing
grand total is 0
required date is missing
vendor is unknown
line items are not itemized
Helpful links:
What procurement rule would you add first: duplicate PO detection, vendor validation, or Slack approval buttons?
I really like your work on this workflow.