A SaaS Startup Automates Signup Verification

A B2B SaaS company integrated the MailTester API into its signup form, blocking disposable and invalid emails in real time and improving trial-to-paid conversion.

## A SaaS Startup Automates Signup Verification *Industry: B2B SaaS* A B2B SaaS company integrated the MailTester API into its signup form, blocking disposable and invalid emails in real time and improving trial-to-paid conversion. ### The challenge The company offered a generous free trial, which made it a magnet for throwaway and disposable email addresses. Fake signups inflated vanity metrics, skewed activation data and meant sales reps wasted hours chasing leads that could never convert. Worse, transactional emails to invalid addresses were bouncing and dragging down deliverability for real users. ### The approach The engineering team added a single MailTester API call to the signup endpoint. Disposable, role-based and invalid addresses are now rejected in real time with a friendly message asking for a work email, while valid signups flow straight through. The result is scored, so genuinely risky-but-real addresses are allowed but flagged for the sales team. ### The results - **Disposable and invalid signups blocked at the door — down 94%** - **Trial-to-paid conversion up 21% as sales focused on real prospects** - **Transactional email bounce rate cut from 4.1% to 0.6%** > “It was a two-hour integration that instantly cleaned up our funnel metrics and our deliverability. I don't know why we waited.” > > — VP of Engineering, B2B SaaS platform ### Get the same result Every one of these outcomes came from the same foundation: verifying email addresses before sending. You can [check an address free](/), automate it with the [MailTester API](/api), or read the [email deliverability guide](/email-deliverability-guide) to plan your own clean-up. Explore more results in our [case studies](/case-studies).