The SaaS Podcast - SaaS, Startups, Growth Hacking & Entrepreneurship 456: Mailtrap: From 20,000 Email Disaster to 7-Figure SaaS - with Sergiy Korolov
Oct 9, 2025
Sergiy Korolov, Co-CEO of Railsware and co-founder of Mailtrap, shares a riveting journey from a 20,000-test-email fiasco to crafting a seven-figure SaaS success. He explains how releasing an internal tool to the Rails community sparked viral growth and the slow pivot from blocking to sending emails. Discover his insights on using customer interviews for pricing strategies, the surprising role of signup surveys, and validating features with a fake menu item. Sergiy also delves into the challenges of scaling and competing in the email delivery space.
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Catastrophic Test Email Mistake Sparked Mailtrap
- Sergiy accidentally sent 20,000 test billing emails from staging to real customers, causing major confusion and anger.
- That mistake led him to build Mailtrap as a staging email blocker and release it to the Rails community.
Build For Yourself, Win The Community
- Mailtrap grew purely through word-of-mouth after being useful to the Ruby on Rails community.
- Serving your own team's needs can reveal a product that scales beyond your company.
Validate Pricing With Data And Interviews
- Use product analytics and >100 customer interviews to shape pricing and roadmap decisions.
- Measure assumptions with data before charging or prioritizing major features.
