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Automation: my cron job sent 10,000 emails to myself

General Discussion by pieter_rtm 5 replies 371 views
pieter_rtm

Member OP

10 #1

To be honest, this is embarrassing. As said, I am precise. Usually.

The job:
- cron on Debian 12 VPS at OVHcloud
- daily report, 06:00 Europe/Paris
- python script, email via postfix to myself

The failure:
- 10,000 emails to myself
- 7 days to notice
- 14GB of "daily report"

Root cause: timezone math. Cron was UTC. Script interpreted "daily" as "every 86400 seconds from first run." First run: 2026-02-07 06:00 CET = 05:00 UTC. Next: 05:00 UTC + 86400s = 05:00 UTC next day. But cron fired at 06:00 CET = 05:00 UTC. Overlap. Race. Every minute for a week.

Spec of the mess:
- 10,247 emails
- 14.3 GB received
- 847 MB log files
- 0 permanent damage

Containers before it was cool
Doug

Member

New Jersey

#2

#10,000 #emails #is #not #a #bug #it #is #a #feature #of #enthusiasm #your #server #loves #you #very #much #hashtag #relationship #goals #no #exceptions #ever

grabs popcorn, checks /r/drama
LI

Member

#3

I had cron run every minute, not every day, because timezone same but different. Your math is bad math, very bad math. 10,000 email is many email. You are famous now, same but different.

NUT

Member

Bangkok

4 #4

😬 lol nice

LifeZoe

Member

#5

The 14gb of daily report is the part that got me

Doug

Member

New Jersey

#6

What was the actual cron expression?

grabs popcorn, checks /r/drama

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