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Acceptable Use Policy

What you may and may not do with isBusinessEmail: fair use, no reselling, scraping, spam, list-washing, limit evasion or multiple accounts.

version
2026-10-04
effective
last updated
controller
Tilfortis MB, Lithuania

This policy is part of our Terms of Service. It exists so the Service can stay free, fast and trustworthy for everyone.

Good uses

These are what isBusinessEmail is for:

  • Checking addresses at signup, on lead forms and during onboarding
  • Routing leads and customers by work vs personal email or by Google Workspace / Microsoft 365
  • Reducing trial abuse and fake accounts
  • Classifying and enriching contacts you already have a lawful relationship with, within your limits
  • Building integrations and tools for your own product or your clients’ products, where each client uses its own account and key

Not allowed

Reselling and wrapping

  • Reselling, sublicensing or renting access to the API or its output.
  • Offering a product or API whose main value is our verdicts or data (for example “email classification API powered by isBusinessEmail”), whether paid or free, without written permission.
  • Sharing one account’s keys across unrelated organizations.

Building a product that uses isBusinessEmail as one part of a larger feature (for example, your signup flow, your CRM’s enrichment step) is fine.

Scraping and sweeping

  • Systematically checking domains or addresses to copy, rebuild or publish our dataset, lists or verdicts.
  • Enumerating addresses at a domain, or sweeping a domain to discover which addresses are blocked.
  • Automating the public website checker, or calling its internal endpoints from scripts. Use a free API key instead.

Spam and list-washing

  • Using the Service to clean, validate or segment lists of addresses you don’t have a lawful basis to email.
  • Supporting unsolicited bulk email, phishing or fraud.

Getting around limits and protections

  • Creating multiple accounts to get more quota or to evade a suspension.
  • Rotating keys, IP addresses, networks or user agents to avoid rate limits.
  • Bypassing, solving at scale, or interfering with robot protection (for example Turnstile) or our anti-abuse measures.
  • Hiding the origin of requests to make publishable keys work from origins you don’t own.

Security and infrastructure

  • Probing, scanning or testing our systems beyond what our security policy allows.
  • Load testing, denial-of-service, or any traffic meant to degrade the Service.
  • Attempting to access other accounts, keys or data.

Unlawful or harmful use

  • Anything that breaks the law, including data protection, anti-spam and anti-discrimination law.
  • Using verdicts as the sole basis for decisions with legal or similarly significant effects on people without the safeguards the law requires.
  • Submitting anything other than email addresses and domains you’re checking (no special categories of personal data, no free-text personal data in feedback).

How we enforce this

We monitor for abuse patterns: unusual sweeps, keys used from many networks, linked accounts, bursts against the public checker. Depending on severity we may:

  1. contact you and ask you to change how you use the Service;
  2. lower your limits or revoke specific keys;
  3. suspend the account temporarily;
  4. close the account and block related accounts, networks or keys.

For serious or deliberate abuse we may act without notice. If you think we got it wrong, reply to the suspension email or write to hello@isbusinessemail.com, and a person will review it.

Not sure?

If you’re unsure whether your use is allowed, or you need more than the standard limits, ask us first. We say yes to most reasonable requests.

Changes

Version Changes
2026-10-04 First version.