How to recover overdue payments with automatic email reminders

1. Why a reminder only works when it comes from a person

The mistake almost every collections tool makes is sending the notice from an address like accounts@ or noreply@. The client reads it as a machine chasing them, parks it and never answers. There is nobody on the other side to reply to.

In the circuit we set up, the reminder goes out from the inbox of the person who actually handles collections in your company. If your administrator is called Marta, the email arrives signed by Marta, from Marta's account, and when the client answers, the answer lands in Marta's inbox. It is an ordinary email between two companies, except a system wrote it and scheduled it.

That is half of what makes it work. Collecting an invoice is an administrative matter between departments, not a campaign. It leaves a documented trail, it is addressed to the client's admin contact and it sounds like a colleague reminding you of something, not like a debt collector. The other 50 % is the cadence and the escalation, which we cover below.

2. The actual circuit, step by step

What follows is the setup we implement, not a theory. Four pieces chained together. None of them is magic; the point is that they work together and that nobody has to remember anything.

• Detecting overdue invoices. The system reads your accounting or invoicing software and every morning flags which invoices have passed their due date and by how many days. If you still type invoices in by hand, the previous step is digitising that entry with invoice OCR, because a collections circuit runs on clean data and reliable dates.
• Reminder cadence. Depending on how many days each invoice has been overdue, one email or another goes out, with a tone that moves from gentle to firm. All of it by email, always from the collections person's inbox.
• Escalation to a person. When a client ignores two or three notices, the system stops sending automatic emails and alerts your manager so they can call or write by hand. The machine chases the routine cases; the person steps in where judgement is needed.
• A record of what was sent and when. Every email sent is logged: who it went to, which invoice, which day, which version of the text. If there is an argument tomorrow about whether the client was notified, you have the full trail.

3. The cadence: when to write and in what tone

Sending the same email five times does not work. The sequence starts before the due date (a friendly heads-up prevents half the delays, which are simple oversights) and hardens in tone as the days pass. This is the base cadence we use; it is adjusted per client and per sector.

Notice that the last step is no longer an automatic email: it is a person. Automation covers the first notice through the third. From there on, human judgement takes over.

4. The human control that prevents embarrassing mistakes

A collections circuit that runs on its own with no brakes is dangerous. A firm email to your best client, who as it happens paid by transfer yesterday, costs you the relationship. That is why the dashboard rules over the automation, and not the other way round.

Mark as paid

As soon as the money comes in you mark the invoice as paid (or the system detects it when reconciling with the bank) and the whole pending sequence for that invoice cancels itself. Zero risk of chasing something already collected.

Pause a specific client

You are renegotiating a deadline with a client, or a project is on hold, or you simply want to handle it by hand. You pause them and they stop receiving automatic emails until you reactivate them. The rest of your ledger keeps running.

Force a send or leave a comment before it goes out

Sometimes you want to bring the next reminder forward without waiting for the date: you force it. And on the more delicate notices (the +15 day one, for example) the system can ask for your approval before sending, so you can add a line or change the tone. You write a comment, you review, and out it goes. Nothing is sent blind unless you want it to be.

5. What the law says (and what you should not promise)

Chasing a payment has a legal framework, and it pays to be clear about it so you can write the emails without bluffing. In Spain it is set by Ley 3/2004 on combating late payment, amended by Ley 15/2010.

The default payment term between companies is 30 calendar days from receipt of the invoice or from delivery. It can be extended by agreement, but never beyond 60 calendar days. That is the legal ceiling.

When a B2B invoice goes past its term, you are entitled (articles 7 and 8 of Ley 3/2004) to late payment interest, which is the European Central Bank reference rate plus 8 percentage points, and to a flat compensation of 40 € per invoice for collection costs, without having to claim it expressly. It is a fact you can mention politely in the third reminder: point out that it exists, do not open with it as a threat.

Two important warnings. One: this is general information, not legal advice; for a serious non-payment, talk to your lawyer or your accountant. Two: do not promise outcomes in the emails and do not take for granted interest you have not calculated yet. The point of a reminder is to get paid sooner, not to win a lawsuit.

6. A real case: an events company we work with

We built this circuit for an events company we work with. They invoiced agencies, hotels and city councils, with long payment terms and one administrator who spent part of her week chasing payments by phone and rewriting the same email over and over.

The problem was not that clients did not want to pay. It was that invoices got lost inside other people's departments and nobody remembered them in time. A friendly notice three days before the due date solved a good share of the delays, but sending it by hand, invoice by invoice, was not sustainable.

We connected their invoicing software, switched on overdue detection and the cadence in the table above, all of it going out from their collections manager's inbox through Microsoft 365. The change in routine is the one you actually feel: she went from chasing payments several mornings a month to reviewing a dashboard for a few minutes a week, marking invoices paid, pausing two clients under renegotiation and approving the delicate notices. The routine reminders went out on their own.

The detail that matters to us: almost no client noticed there was a system behind it, because the emails were indistinguishable from the ones the person used to send by hand. Which is exactly what we were after. For the detail of how this rests on having invoices properly digitised, we wrote the guide to AI invoice OCR.

7. When this is NOT worth building

Not everyone needs this circuit. We are the first to tell you not to build it if your case is one of these:

• Monthly invoices you can count on one hand. If you issue five or six invoices a month and know every client by name, a well placed manual reminder is more than enough. Automating here is using a sledgehammer to crack a nut.
• Dirty data, or no invoicing software. If due dates are not properly recorded, the system will fire the wrong notices and you will lose your clients' trust. First you tidy up how invoices come in (this is where OCR does help), and only then do you automate collections.
• The problem is not forgetfulness, it is insolvency. If a client is not paying because they cannot or will not, no email fixes that. That is the territory of a formal claim and your lawyer, not of a polite cadence.
• Relationships where the personal touch is the business. With a handful of large, sensitive accounts, a call from the manager is sometimes worth more than any sequence. Automate the long tail of small clients and keep the big ones for the person.

8. Why this goes by email and not by WhatsApp

We get asked this a lot, so let us be clear. Claiming money from another company is an administrative matter: it has to be in writing, leave a trail, and be addressed to the client's admin department, not to anyone's personal phone. That channel is email, and only email.

We use WhatsApp for something different: waking up dormant clients, first commercial contact and support. That is sales, not collections. If that part interests you, we cover it in sales automation on top of your CRM and in the WhatsApp chatbot for companies. But do not use WhatsApp to chase an overdue invoice: it reads as informal, the trail is lost and it mixes sales with administration. Collections belong to email.

Frequently asked questions

Sources

• Ley 3/2004, de 29 de diciembre, por la que se establecen medidas de lucha contra la morosidad en las operaciones comerciales (Boletín Oficial del Estado (BOE))
• Ley 15/2010, de 5 de julio, de modificación de la Ley 3/2004 (plazos de pago de 30 y 60 días) (Boletín Oficial del Estado (BOE))
• El esfuerzo financiero de las pymes como consecuencia de la morosidad se cifra en 1.957 millones de euros (CEPYME, Observatorio de Morosidad)
• El plazo medio de pago baja en 2025, pero sigue un 34 % por encima del límite legal (El Diario de Madrid)

Keep reading