APIddress — email validation API

Beyond the six core verdicts, APIddress provides extra signals that help users make informed decisions. When an email has a common domain typo, the API returns a suggested correction, reducing user frustration and preventing accidental data loss. For 'risky' verdicts, the system checks whether the domain is a catch-all, where any address at the domain might accept mail but not be individually valid. It also scores the sender reputation of domains, flagging those known for low trust. These additional insights are surfaced as part of the response, giving developers the context to implement custom logic — for example, routing risky addresses to a separate queue for manual review rather than immediately blocking them.

APIddress works by combining multiple verification layers into a single API call. When a request is made, the service first checks syntax against RFC standards. If malformed, it returns immediately without further processing, saving resources. Next, it queries the domain’s MX records to confirm the domain can receive mail. If no MX records are found, the address is marked undeliverable and a typo suggestion is offered. Then it checks if the domain belongs to a known disposable provider. After that, it performs a mailbox existence check by connecting to the mail server to confirm the inbox exists. It also determines if the address is role-based or part of a catch-all. Each check is executed in parallel where possible, and the results are combined into a JSON response listing the verdict and all supporting signals. The entire workflow is documented in the API docs and accessible via a simple RESTful interface.

Concrete use cases demonstrate APIddress’s impact. For signup and onboarding, blocking fake and mistyped emails at the form reduces fake signups by 31%, ensuring every new account is reachable from day one. For checkout and receipts, confirming the buyer’s address before payment increases receipt delivery by 4.2%, improving customer satisfaction and reducing support tickets. For list and CRM cleanup, scoring millions of existing contacts in batch and retiring addresses that quietly bounce can process 22 million rows per hour, slashing bounce rates. For sender reputation, keeping bounce rates below 0.3% helps maintain domain trust and avoid spam folders. These measurable outcomes — fewer fake accounts, higher delivery rates, cleaner lists, and better sender scores — rely on the API’s granular verdicts and reliable performance.

APIddress is built for developers and teams who manage email-based workflows: SaaS companies onboarding users, e-commerce businesses sending receipts, marketing teams running email campaigns, operations teams cleaning CRM data, and product managers reducing fraud. It integrates via a simple REST API, compatible with any language or platform that can make HTTP requests. The product is currently in pre-launch with open wishlist access. Signing up reserves an API key with 2,000 free validations each month and founding-member pricing locked for a year — no credit card required. The service is GDPR-safe and emphasizes data privacy. In summary, APIddress delivers transparent, actionable email verification that lets teams control their email quality, reduce bounces, and improve delivery, all through a single API that shows its work.