Product-Led Growth: From 20,000 Email Disaster to 7-Figure SaaS | Mailtrap

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. In this episode, Sergiy Korolov (Co-founder of Mailtrap) reveals the SaaS Pricing Strategy behind converting a massive free user base into paid customers. Learn his controversial "Mandatory Survey" tactic that unlocked deep customer insights without hurting conversion, how he used a "Fake Door" test to validate a massive product pivot before writing code, and the specific challenges of expanding from a simple testing sandbox into a full-scale Email API platform. 🔑 Key Lessons 📊 The Mandatory Survey: Why forcing users to answer questions during signup actually helped growth without hurting conversion. 🚪 The "Fake Door" Test: Validating a major feature (Email Campaigns) with a dummy button before building it. 💰 Monetization: Transitioning a free community tool into a profitable recurring revenue business using data-driven pricing. 🛠️ Developer Marketing: How to build a product that developers naturally share (PLG) without a sales team. 🔄 The Pivot: How they navigated the risky shift from blocking emails to sending them reliably in production. 📖 Chapters The 20,000 Email Disaster (Origin Story) Building Internal Tools: The "Eat Your Own Dog Food" Strategy The Decision to Monetize a Free Tool Pricing Strategy: Using Data & Interviews to Find the Price The Onboarding Myth: Why Fewer Clicks Didn't Increase Conversions The Mandatory Signup Survey (That Didn't Kill Growth) The "Fake Door" Test: Validating Email Campaigns Before Building The Pivot: Expanding from Email Testing to Email Sending Competing with Giants (SendGrid, Mailgun) AI for Developers: Hype vs. Reality This episode is brought to you by: 💖 ⁠⁠Sprinto⁠⁠ → ⁠⁠Learn more and book a demo today 🚀 SaaS Club Launch → Build your SaaS to $10K MRR Resources: 🎧 Full Show Notes: saasclub.io/456 🎤 Subscribe to the Podcast: saasclub.io/subscribe 💌 Get weekly 5-minute SaaS insights: saasclub.io/email 💡 Join the SaaS Club founder community: saasclub.co/plus