SMS is 5% of the notifications and almost all of the bill

transcript

Your notification bill: 7.5 million dollars a month. Almost all of it comes from 5 percent of your messages.

A fintech app. 50 million users. 500 million notifications a day. Push carries 60 percent. Email, 25. In-app, 10. And SMS? Just 5 percent.

Now the bill. Push through FCM and APNs: free, beyond your own servers. In-app: about 10,000 dollars of WebSocket servers. Email: 3.75 billion a month, at 10 cents per thousand. 375,000 dollars. SMS: 750 million a month, at 1 cent each. 7.5 million dollars.

Each SMS costs a hundred times an email. So the expensive question isn't how many messages. It's which channel.

So push goes first. It's free. Email second. It's cheap. Digests instead of single emails save 30 to 50 percent more. SMS only for critical alerts, or when push fails. That alone saves an estimated 2 million dollars a month or more.

Even with negotiated rates, SMS runs about 3 million dollars a month. Free first. Cheap second. SMS only when it has to arrive.

Full breakdown in the lecture.