Automatically Email Invoices in WooCommerce (PDF + Custom Design)

If you’re running an ecommerce store, sending invoices manually is a waste of time. This guide shows you how to automatically email invoices in WooCommerce — with professionally branded PDFs attached to every order email. Whether you’re selling B2B, physical goods, or digital products, this workflow is a must.

We’ll cover:

• ✅ How to send automatic PDF invoices on order complete
• ✅ How to customize the invoice design with your logo & layout
• ✅ Code-free and developer-level options
• ✅ Bonus: Attach invoice to customer note and admin emails

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Why Send Automatic Invoice Emails in WooCommerce?

• 🧾 Legal and tax compliance for B2B and international orders
• 📩 Improved professionalism and customer trust
• ⏱️ Saves time vs manually generating invoices
• 🖨️ Easy PDF download for record keeping

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Option 1: Use a Plugin (No Code Required)

🛠 Recommended Plugin: WooCommerce PDF Invoices & Packing Slips

This plugin automatically generates and attaches a PDF invoice to the customer’s order email. It also allows for invoice numbering, logo upload, footer notes, and more.

✅ Setup Instructions:

1. Install the plugin from Plugins → Add New → Search “PDF Invoices”
2. Go to WooCommerce → PDF Invoices
3. Upload your logo and adjust company details
4. Set which email(s) to attach the PDF (Order Completed, Customer Invoice, etc.)

🧠 Bonus:

Upgrade to their Professional extension to:

• Change layout with drag-and-drop designer
• Attach custom terms & conditions
• Send credit notes or proforma invoices

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Option 2: Programmatic Method Using WooCommerce Hooks (Dev Level)

Want to control how invoices are created or emailed? You can hook into order actions and attach your own PDFs.

🧩 Hook into the Completed Order Email

add_filter('woocommerce_email_attachments', 'attach_custom_invoice_pdf', 10, 3);
function attach_custom_invoice_pdf($attachments, $email_id, $order) {
 if ($email_id === 'customer_completed_order') {
 $upload_dir = wp_upload_dir();
 $pdf_path = $upload_dir['basedir'] . '/invoices/invoice-' . $order->get_id() . '.pdf';
 if (file_exists($pdf_path)) {
 $attachments[] = $pdf_path;
 }
 }
 return $attachments;
}

This checks if a PDF exists for the order and attaches it to the email. You’d need a custom function elsewhere to generate and save the PDF.

📄 How to Generate the PDF?

Use libraries like mPDF or DOMPDF to create invoice PDFs dynamically. Here’s a sample of how to create a basic one:

require_once __DIR__ . '/vendor/autoload.php';
$mpdf = new \Mpdf\Mpdf();
$order = wc_get_order($order_id);
$html = '<h1>Invoice #' . $order->get_id() . '</h1>';
$html .= '<p>Customer: ' . $order->get_billing_first_name() . '</p>';
$mpdf->WriteHTML($html);
$upload_dir = wp_upload_dir();
$mpdf->Output($upload_dir['basedir'] . '/invoices/invoice-' . $order->get_id() . '.pdf', \Mpdf\Output\Destination::FILE);

Trigger this after order status is marked as “completed” using:

add_action('woocommerce_order_status_completed', 'generate_invoice_pdf');
function generate_invoice_pdf($order_id) {
 // Your custom PDF generation logic goes here
}

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Customizing the Invoice Design

If you’re using the plugin, go to PDF Invoices → Templates and:

• ✅ Upload your company logo
• ✅ Adjust header, footer, and font sizes
• ✅ Include legal or tax info like VAT or EIN numbers

If you’re using your own PDF library, you can fully style the PDF with HTML/CSS inside the WriteHTML() method.

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Sending Invoices on Different Email Types

You can attach invoices to multiple WooCommerce email types using the same woocommerce_email_attachments filter. Just check for:

• customer_invoice
• customer_processing_order
• new_order (admin notification)

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Final Thoughts

Automatically emailing WooCommerce PDF invoices boosts your professionalism and ensures customers always have the documents they need — without lifting a finger.

Whether you use a no-code plugin or code it from scratch with mPDF or DOMPDF, you’ll end up with a fast, scalable solution that saves time and enhances your brand.

Need help building a custom PDF invoice engine or automating your order flows? Contact Babar Ilyas for custom WooCommerce automation & dev work.

Looking to go deeper? Check out our guide on automating abandoned cart emails or learn to add dynamic checkout fees.