StopReg

StopReg is an email intelligence API for catching disposable, malformed, and risky addresses before they become accounts or enter a lead database. It is designed for developers adding a decision point to registration forms, free trials, lead capture, or other flows that attract temporary inboxes and automated abuse. A request returns structured JSON in real time, giving the application information it can use to allow, warn, or block the submission. The goal is not merely to confirm that an address contains an at sign. It is to classify the domain and address patterns that can signal throwaway use, role accounts, relays, or delivery problems.

The service exposes two validation approaches. Full email validation sends the complete address and checks syntax, disposable status, role based names such as support or sales, public providers, forwarding or alias services, and mail exchange records. A domain only endpoint provides a more privacy conscious option when the application does not need to transmit the local part of an address. That endpoint still checks disposable status, public provider classification, and MX availability. The documentation says StopReg does not store full email addresses and focuses its retained checking on the domain portion, which makes the narrower route useful for teams with stricter data minimization requirements.

Disposable detection is backed by a domain database that the company says is continuously updated through automated discovery, manual verification, and behavioral analysis. StopReg also identifies common free, internet service provider, and educational domains, along with email relay and masking services. Syntax and MX checks catch a different class of problem by establishing whether the address is properly formed and whether its domain is configured to receive mail. These signals arrive together in the API response, so an application can distinguish a temporary inbox from a public mailbox or an invalid domain instead of collapsing everything into a single vague valid or invalid result.

Teams can shape enforcement around their own context. The dashboard supports custom allowlists and blocklists, and the documentation describes policies that can allow, warn, or block according to a domain's classification. A form abuse shield is intended to spot custom or relay domains linked to repeated submissions. Paid plans also include bulk email and domain validation, provider information, API logs, and multiple keys or user seats as plan size increases. This combination matters for products that need exceptions. A school, partner, or customer domain can be explicitly trusted, while a locally observed abuse domain can be blocked even if it is not yet part of a broad disposable provider list.

Integration is built around a REST API secured with an account token. The public documentation walks through email and domain requests, authentication, response handling, errors, rate limits, and implementation examples in several languages. The site links official JavaScript and PHP packages, including an NPM package and a Laravel integration, while plain HTTP requests keep the service usable from other stacks. The result is a conventional server side integration. The token should remain out of browser code, and the registration or lead service can turn StopReg's classification and policy fields into its own product decision.

StopReg fits SaaS teams trying to limit repeat trials, communities dealing with fake members, marketplaces protecting onboarding, and marketing operations that want cleaner lead data. It can also help separate corporate, educational, public mailbox, and relay traffic for routing or analysis. The signals still require a sensible policy. A public provider address can belong to a valuable user, a role address may be intentional, and a configured domain does not prove a particular person is trustworthy. The useful part is the combination of classifications and custom rules, not an assumption that every unusual address should be rejected automatically.

Pricing is freemium. New accounts receive 200 requests each month without a credit card. Paid plans begin with the Launch tier, which the site currently lists at $20 per month for 60,000 requests, one seat, and one API key. Higher tiers increase request volume, keys, and seats, while an enterprise option adds custom capacity, priority support, and a service level agreement. The free allowance is enough to test an integration or protect a very small flow. Production products with meaningful registration volume will likely need a paid tier, and teams should compare the cost with their expected request rate and how many environments need separate keys.