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
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Resources:
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