How to Automate Invoice Collection from Email (Step-by-Step Guide)

If you're still manually searching your inbox for invoice attachments every month, you're spending time that should be automated. The good news: connecting your email to an invoice automation tool takes about 5 minutes, and once configured, you never have to search for an invoice email again.

This guide covers how to automate invoice collection from Gmail, Outlook, and shared inboxes, and what to look for in a solution.

Why Email Is Still the #1 Source of Invoices

Despite the rise of accounting portals and e-invoicing mandates, the majority of B2B invoices still arrive as PDF attachments to emails. A 2024 survey of EU SMBs found that 74% of incoming supplier invoices arrive via email. WhatsApp is second at around 15%, followed by cloud portals (Google Drive, Dropbox shares) at 8%.

This means automating your email is the highest-leverage change you can make to your invoice workflow.

Step 1: Connect Your Email Account via OAuth

The safest way to grant an automation tool access to your email is via OAuth. The same standard used by "Sign in with Google" or "Sign in with Microsoft." OAuth grants read-only access to your inbox without sharing your password with any third party.

In Invoflux, go to Settings → Connections → Add Email Account. You'll be redirected to Google or Microsoft's authorization screen, where you grant read-only permission to attachments. Invoflux never sees your password and can never send or delete emails.

What permissions to look for: The request should ask only for mail.readonly or equivalent. If an invoice tool asks for send/delete permissions, that's a red flag.

Step 2: Configure Which Emails to Scan

You don't want every email with a PDF attachment treated as an invoice. Configure filters to focus on invoice-relevant emails:

• Sender allowlist: Add your regular suppliers' domains (e.g., @aws.amazon.com, @google.com)
• Subject keywords: "invoice", "factura", "rechnung", "faktura"depending on your suppliers' languages
• Attachment types: PDF and image files only
• Folder filters: Scan only your Invoices label/folder if you use Gmail labels

Invoflux's AI also performs a secondary classification step. It looks at the content of the PDF to confirm it's actually an invoice before extracting data, reducing false positives from things like shipping labels or contracts.

Step 3: Set Up Shared Inboxes

Many companies receive invoices at a shared address like [email protected] or [email protected]. These shared inboxes are often connected to Google Workspace or Microsoft 365.

In Invoflux, you can connect shared inboxes with a service account or delegated access. The account owner grants access once, and all invoices arriving at that address are automatically processed.

Step 4: Handle WhatsApp and Other Sources

Once email is automated, add your secondary sources:

• WhatsApp Business: Suppliers who send invoice photos or PDFs via WhatsApp. Invoflux connects via WhatsApp Business API.
• Google Drive / Dropbox: If suppliers share invoice folders with you, Invoflux monitors these for new files.
• Mobile camera: For paper invoices, the Invoflux mobile app lets you photograph and instantly process a physical invoice.
• Cloud vendor portals: AWS, Google Cloud, Meta Ads, and other vendors have portals where you normally download invoices manually. Invoflux automates this monthly download.

Step 5: Review and Export

Once invoices are collected, Invoflux's AI extracts key fields. Supplier, date, invoice number, amount, VAT. You review flagged items (usually <5% of invoices), then export to your accounting software or share with your accountant.

The whole review cycle for 50 invoices typically takes under 10 minutes once automation is running.

What About GDPR?

For EU businesses, data residency matters. Ensure your invoice automation tool processes and stores data in the EU. Invoflux is hosted entirely on Hetzner infrastructure in Frankfurt, Germany. No data leaves the EU. All connections use TLS 1.2+, and data at rest is AES-256 encrypted.

Summary: The 5-Minute Setup

1. Connect Gmail or Outlook via OAuth (read-only)
2. Set sender/subject filters to focus on supplier emails
3. Add shared inboxes if applicable
4. Connect secondary sources (WhatsApp, Drive, portals)
5. Review the first batch, then let automation handle the rest

The result: every invoice from every source lands in your dashboard automatically, with data extracted and ready for review. No more email archaeology at month-end.