Five anti-abuse patterns for an uncapped trial referral system

A developer who built a referral extension for a trial product found that uncapped invites were being exploited, with throwaway inboxes used to self-invite. Their fix was to grant bonus days only after an invitee takes a meaningful action, such as successfully mounting a drive, rather than at signup. Additional safeguards included limiting invites to three per day, excluding known disposable email domains, and an opt-in duplicate-user check. After deploying these patterns, self-invites dropped below 2 percent and power-abuser value fell from roughly four years to about six months. The author argues that such strict defenses suit low-priced lifetime products but may be less appropriate for subscription or network-dependent software.