After deciding I couldn't sustain the product with a feemium model, I made it paid only. People can have a play with the service for free, but to actually start sending newsletter issues, they'd have to sign up as a paid user. This is when Letterfuel started making some actual income, although it's very small right now.
Product Hunt launch
After pushing the launch for way too long, I finally launched on Product Hunt (even though I really wasn't happy with the state of Letterfuel). The launch went well, but it led to hardly any paying customers...
Started work on Letterfuel
After mulling the idea over for probably over a year, I started working on Letterfuel. I didn't really validate the idea and had no idea if it would work, but I wasn't working on any other side projects at the time and wanted a challenge technically.
I've been running a newsletter (uimovement.com) for years and I build an internal tool to make the process of putting it together so much easier. I figured others would find the tool useful too.