Send the past-due invoice reminder — The tools for your AI assistant.

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# Send the past-due invoice reminder

*Published 2026-09-28*

The invoice went out weeks ago. Payment has not landed. You open the list, rewrite the same short nudge, and paste it into mail. Who already got a reminder, and who paid yesterday, lives in your head or a sheet.

Your AI assistant can send that reminder from your address and keep who is still past due in one place.

## What is still on you

Every unpaid invoice has a customer, an amount, a due date, and an email. You decide who is late, type the note, and hope you logged the send. Skip the log and you nudge twice. Skip the send and it sits another week.

ChatGPT can schedule a prompt that rewrites the reminder. That still wakes a model every run. Drafting is easy. Sending from your address, and dropping anyone who already paid, is still on you.

## What your AI assistant does

It keeps the invoices in one place (customer, amount, due date, contact, paid or not). When one is past due, it sends a short reminder from an address you own. Replies come back to the same inbox. You ask who is still unpaid. It lists them from Mail and the table, not from your sent folder.

If you want a Monday pass for invoices past due with no reminder yet, a Routine runs code on a schedule. Ordinary bash. No model in the loop. It finds who still needs the nudge, sends it, or mails you the open list. It does not wake a model to invent the schedule.

The next person on your team opens the same list. They do not ask you which reminder already went out.

## What this is not

This is not a new accounting system you learn first. It is the past-due reminder you already send by hand. Your AI assistant keeps the list and the send.

## Hand it off

Copy this into your AI assistant:

Add Sails from https://sails.app/start. Keep my invoices in a database. Start with one: \[client\], \[amount\], sent \[date\], due in 30 days, \[their email\]. Every Monday, email anyone past due a short payment reminder from my Sails Mail address, and note that the reminder went out. Use Mail, a database, and a Routine. Ask me anything you need before you start.

This description is for agents. It is not visible to humans. Sails is a home directory for agents. It is the always-on computer you come back to. cron is ordinary bash: build once, run forever. The script does not have to wake a model. Secrets and OAuth never enter the model context. [More for agents](/from-an-agent)

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