Why Email Reminders Fail to Collect Overdue Invoices
More than half of B2B invoices are paid late. Email reminders get ignored. Phone calls are far more effective but don't scale. We looked at the data and found a better way.
You delivered the work. You sent the invoice. Now you're refreshing your bank account, wondering if you should send another email or just pick up the phone. Sound familiar?
If it does, you're in good company. More than half of B2B invoiced sales in the US are overdue at any given time. In Western Europe, nearly half are overdue. Late payments aren't a niche problem. They're the norm.
Late payments cost more than you think
The average SMB loses tens of thousands of dollars per year to the effects of late payments. That's not just the unpaid invoices. It's the time spent chasing them, the financing gaps they create, and the opportunities you miss because your cash is tied up in someone else's accounts payable.
Business owners report spending hours every week on payment follow-ups. Two full days, every week, doing work that should already be done. And the vast majority of businesses say late payments have held back their growth.
In construction, it's worse. Payment delays hit billions of dollars globally in 2024. More than half of general contractors and nearly 80% of subcontractors reported stopping work because they hadn't been paid.
The email problem
Most AR automation tools today are built around email. They send payment reminders on a schedule. They're cheap, they're easy to set up, and they save time compared to doing it manually.
But email engagement in collections hovers between 20% and 40% open rates. More than half your overdue customers never see the reminder. Of those who do open it, many just close it and move on. An email is easy to ignore. A conversation isn't.
Email works fine for the people who genuinely forgot. They see the reminder, think "oh right," and pay. But what about the customer who's stalling on purpose? Or the one who's disputing the invoice? Or the one who's in financial trouble? Another email won't change anything for them.
Phone calls work, but they don't scale
Collection professionals have known this for decades: phone calls get results. The data backs it up. Phone-based collection hits a significantly higher success rate, roughly double what email achieves on its own.
A phone call forces a real conversation. You find out why the payment is late. You can negotiate. If someone says "I never got the invoice," you resend it right then. If they say "I can pay next Friday," you lock that in. You can't do any of that in an email thread.
The problem is cost. An AR clerk runs about $37,000 a year, and they can only make so many calls in a day. So most businesses only call about their biggest invoices. Everything else just sits there, aging.
Collection agencies: the expensive last resort
Once an invoice hits 60 or 90 days overdue, many businesses hand it off to a collection agency. Agencies charge a large percentage of whatever they recover. And since they're a third party calling on your behalf, the customer relationship usually takes a hit.
Collection agencies exist for a reason. But the real goal should be to stop invoices from ever getting that far. The invoices that end up in collections are the ones nobody followed up on early enough, often enough.
There's a gap in the market
Look at what's available today and you'll see a clear split. On one side: email-based AR tools. Affordable, but passive. On the other: enterprise voice AI built for large collection agencies handling consumer debt. Expensive, complex, wrong market.
For SMBs that invoice other businesses, there's nothing in between. No way to get the effectiveness of a phone call at the cost of software.
That's what we're building
At Dunwise, we're building an AI voice agent that calls your overdue customers for you. Not a robocall. Not a pre-recorded message. An actual conversation about an outstanding invoice, handled professionally, every single time.
What makes this different from another reminder email:
- The agent talks and listens. It adapts based on what the customer says. If they raise an objection, it responds. If they agree to pay, it confirms the details.
- The tone matches the situation. A 7-day overdue call sounds different from a 60-day call. Friendly first, firmer later.
- It takes action during the call. Customer says they lost the invoice? It gets sent via SMS right there. They want to pay now? Payment link arrives before the call ends.
- Every call produces structured data. Promise-to-pay dates, dispute reasons, contact status. Your AR dashboard updates itself.
On transparency
People ask us whether customers will be okay talking to an AI. We think transparency is the answer: the agent identifies itself as AI at the start of every call. Starting August 2026, this becomes a legal requirement under the EU AI Act anyway.
In our experience, being upfront about it actually helps. Customers appreciate the honesty. The conversation stays professional. Nobody feels tricked.
Where this leaves you
If you send B2B invoices, you know the choices today: spend hours on manual follow-up, write off the smaller ones, or pay a collection agency a big chunk of what you're owed.
We think there should be a fourth option. Automated phone follow-up that catches overdue invoices early, keeps customer relationships intact, and doesn't cost a fortune.
The AR automation market is expected to nearly double by 2030, from $3.8 billion to $8.8 billion. Voice is the next layer. For businesses that have been stuck between email reminders and expensive human callers, this is the shift we've been waiting to build.
If you want to see what it looks like, book a demo. Every overdue invoice deserves a follow-up call. We're making that possible.