---
title: "One Reminder Email, Three Copies, Seven Seconds Apart"
canonical: https://dxdev.com/everyday-ai/one-reminder-three-copies/
datePublished: 2026-10-01
---
One scheduled reminder email reached our inbox three times on the same morning: once at 4:14 and twice at 10:06. The first copy arrived on schedule. The other two did not.

## What had changed

For two and a half years, the job behind that email had run exactly once a day. Then, starting September 17, days with extra runs began to appear: the 17th, 22nd, 23rd, 24th, 25th, 26th, 28th and 29th, and then October 1. Before this, we had counted 161 duplicate sends.

Nothing in that history looked like a single bad morning. It looked like a new habit.

## The guard we already had

On September 22 and 23 we added a guard, after earlier duplicates. It stops two runs from happening at the same time.

On October 1 the problem was a second run starting after the first. The guard was never built to stop that, so it did nothing here. We had fixed a real problem, just not the one in front of us.

## Why only one email tripled

The job also tries not to email the same person twice in a day. It checks whether a given person has already been sent that day's message.

This reminder goes to a fake "Support Staff" recipient with no person record behind it. With no person to look up, the check never applies, and the reminder went out again every time the job ran.

## Where the extra runs came from

The server's log of incoming requests showed two, at 10:05:53 am and 10:06:00 am. That is seven seconds apart, and each one started the early-morning job again. That job sends real email.

The log could not say which tool made them. A note in our records says a restored browser tab re-ran the job and re-sent email on October 1.

## The numbers, side by side

Three copies of one email arrived. The first came at 4:14 and was the scheduled one. The two at 10:06 were repeats.

Two requests arrived seven seconds apart, at 10:05:53 am and 10:06:00 am, and each one started the job again. The 161 duplicate sends were counted earlier, before October 1. The run history shows one run a day for two and a half years, and days with more than one run from September 17 to October 1.

The guard went in on September 22 and 23, and extra-run days still showed up on the 24th, 25th, 26th, 28th and 29th, and on October 1. A guard against runs happening at the same time had no way to change that count, because the extra runs were a different kind.

## What we are left with

One email, three copies, two requests seven seconds apart, and a guard aimed at the wrong kind of repeat. The reminder to the fake recipient tripled because it was the only one the "already sent" check could not see.