Keeping our free tier sustainable by preventing abuse

This pattern is everywhere. It was foreign to me for a long time because I'm the type of person who likes to play within the rules. There are a lot of people who get a kick out of gaming the system to their advantage, even to the point of breaking the law.

Many people have zero qualms about stealing things when they imagine it's a faceless corporation on the other side. They might even rationalize it with mental gymnastics until they think they're doing the right thing. You see it most often when the topic of media piracy or sharing Netflix logins comes up.

This mindset is very common in startup communities. I've heard so many stories from founders gloating about how they abused some system or used a loophole to avoid paying for something they could clearly afford. It's like a badge of honor to some people. I know one guy who bought an EV but hasn't installed a charger because he drives it to a business down the street and uses the EV charger they installed for their employees every night. Another guy used to brag about sneaking into a cafeteria for another organization and stealing lunch every day. A while ago I talked to a guy who liked to "dine and dash" without paying his tab, even though he could easily afford it. For them, it's all about getting away with it and winning a game.

As soon as you make it obvious that someone is watching them, they cave. They don't want to be the type of person who abuses actual people. They only like to abuse what they see as faceless systems.

For paying customers, it probably doesn't make a lot of sense to use an anonymous email address, since we ask for your name and billing address either way (have to stay compliant with sales taxes!)

I would probably not recommend implementing a whitelist for blocking purposes. But perhaps domains on a whitelist could get a slight scoring bump.

[1] https://github.com/disposable-email-domains/disposable-email... [2] https://github.com/disposable/disposable [3] https://github.com/unkn0w/disposable-email-domain-list

I suppose you could call it inspired by Bayesian inference since we're using multiple pieces of independent evidence to calculate a score, though that makes it sound a bit fancier than it is and we aren't using the Bayes' theorem. But it's possible I had that in the back of my head from a game theory class I took long ago.

But for the fun of it, let's model it that way:

Probability (Spam | disposable email domain, IP address, etc... ) = [probability(disposable email domain, IP address, etc... | spam) x prior probability(spam rate)] / probability(disposable email domain, IP address, etc...)

Or something like that.

Also — it's a delight to have one of Patrick's articles mentioned in connection with this!