If you go make an API key in Fastmail (Settings -> Password & Security -> API tokens), you'll see that it's prefixed very similarly to that (e.g. `fmo1-`) for t

If you go make an API key in Fastmail (Settings -> Password & Security -> API tokens), you'll see that it's prefixed very similarly to that (e.g. `fmo1-`) for this very reason! (There are some other neat things about our API key format I'd be happy to tell you about sometime if you're interested.)