How Second Legacy keeps referral campaigns — and client databases — free of fake signups
Second Legacy runs growth and product for a portfolio of SaaS and creator brands. Every one of them has a signup form, a referral campaign, or a waitlist that fake emails, disposable domains and bot networks love to abuse. FishyMails sits in front of all of it.
The problem
Referral campaigns are magnets for abuse. When Second Legacy launched a viral referral flow for HELLO Labs, the first 48 hours brought thousands of signups — and a large slice of them were disposable addresses, typo domains, and coordinated bot rings farming referral rewards.
On the SaaS side the pain was quieter but more dangerous: over months, fake emails silently degraded sender reputation, blew up transactional bounce rates, and corrupted product analytics on cohorts, activation and retention.
Why FishyMails
Second Legacy needed one API they could drop into every client stack — Next.js landing pages, TanStack Start apps, Zapier flows, Supabase edge functions — without hand-rolling different validators per project.
Reputation protection
Every signup email is scored before it ever hits Postmark, Resend or Mailchimp. Disposable domains, catch-alls and spam traps are blocked at the door.
Referral campaign guardrails
For HELLO Labs, referrals are only credited once the referred email passes an IP + email risk check — killing the incentive to farm rewards with throwaway accounts.
Clean SaaS databases
Client tenants stay free of junk rows. Product analytics on activation, retention and MRR reflect real humans, not bots.
One API, three checks
Email, phone and IP reputation from a single endpoint — the same key works across every Second Legacy client project.
"FishyMails is one of the few tools that pays for itself in the first campaign. Our clients get real users, real deliverability and real referral numbers — instead of a database full of noise."
Protect your next campaign
100 free credits to start, no card required. Enough to protect a real referral launch end-to-end.