Back in 2011, Sergiy Korolov's team accidentally sent 20,000 test billing emails to real customers—a complete disaster. They built a simple internal tool to prevent it from happening again, shared it with the Ruby on Rails community, and it exploded. Fast forward to today: Mailtrap generates seven-figure ARR with 100,000+ monthly active users. The journey wasn't easy. For five years, Mailtrap was just a free side project. When Sergiy finally monetized in 2016, growth was slow and methodical—it took four more years to hit $1M ARR. Then came the biggest challenge: pivoting from a tool that blocks emails to one that sends them in production. It meant rebuilding infrastructure, fighting brand confusion, and competing with giants like SendGrid and Mailgun. You'll learn: How making signup surveys required provided deep customer insights without hurting conversions How a fake "Email Campaigns" button validated product demand before building anything Why community trust and developer-first thinking beat flashy marketing every time How they navigated the risky pivot from blocking emails to sending them reliably Why running 100+ customer interviews shaped their entire pricing and roadmap strategy Full show notes → saasclub.io/456 This episode is brought to you by: 💖 ⁠⁠Sprinto⁠⁠ → ⁠⁠Learn more and book a demo today 🚀 SaaS Club Launch → Build your SaaS to $10K MRR Get weekly SaaS lessons and new founder stories → saasclub.io/email