Spotify is one of the world’s largest online music streaming services and sends billions of marketing emails to its users every year. However, in December 2020 the team responsible for email campaigns was contacted by Twilio SendGrid – the platform it uses to manage email marketing – and was told that it was close to being shut down.

Why? Because Spotify didn’t realize that it was sending millions of emails to what are known as ‘spam traps’: bad actors that are looking to harm Spotify’s systems. Matt Gioe, Engineering Manager at Spotify, and the person heading up the email campaign office, was speaking at Twilio’s Signal event this week, where he warned other organizations that they need to get to grips with both the art and science of email, in order to avoid a similar situation.

The problem was brought to Spotify’s attention in December 2020, during the company’s largest campaign of the year, Holiday 2020. During this time Spotify sends approximately 1 billion emails to 170 email subscribers across 92 countries over roughly a 30 day period. It was in the middle of this huge campaign that Twilio SendGrid got in touch. Gioe said:

I received a series of pretty frantic emails, messages and phone calls from three Twilio employees, two of them who I’ve worked with before, and one that I’d actually never heard of.

It turns out this third person was Len Shneyder, who is the VP of Industry Relations at Twilio. Len wanted me to know…that if I don’t do something, I’m going to get shut down…and by me, he really meant Spotify, and by Spotify he meant all of Spotify’s emails. So this is pretty terrifying.

This kind of came out of the blue. This was actually my first marketing campaign that I’d ever worked on. But you can imagine that I was not having a great day.

Read more: How Spotify almost had its email marketing shut down because of spam traps