CheckMXTerms of Service
Last updated: October 25, 2026 · Contact: hello@checkmx.dev
What you're agreeing to
These terms cover use of the CheckMX dashboard, the /api/verify HTTP API, the checkmx CLI, and the Claude MCP integration (together, "the Service"). By signing in, calling the API with a key, or otherwise using the Service, you agree to these terms.
The Service
CheckMX checks whether an email address is likely to accept mail, and returns one of four verdicts (deliverable, undeliverable, risky, or unknown) along with supporting signals (disposable, role account, catch-all). Email checks are included free with every CheckMX plan. Current plans are posted at checkmx.dev/#pricing and are part of these terms by reference. We'll update that page, not this one, when plans change.
Privacy and Google connections
Our Privacy Policy explains how we handle your data. Connecting a Google account and using its Gmail features is subject to that policy. For support, contact hello@checkmx.dev.
Email checks
- Email checks are included free with every plan, including the free Sandbox, and are not sold separately.
- Use email checks for addresses you have a legitimate reason to contact. Access is non-transferable between accounts.
- Duplicate lookups may be served from cache or deduplicated within a batch request.
unknownor deferred results can be retried.
Acceptable use
You may not use the Service to:
- Facilitate spam, unsolicited bulk email, or any campaign that violates CAN-SPAM, GDPR, or equivalent anti-spam/data-protection law in your jurisdiction.
- Verify addresses obtained through scraping, breach data, or any source you don't have a legitimate basis to contact.
- Attempt to circumvent rate limits, probe our verification infrastructure for purposes other than legitimate verification, or resell raw API access without a separate agreement with us.
- Reverse-engineer, decompile, or attempt to extract the verification logic or infrastructure behind the Service.
We enforce per-key rate limits (documented alongside the API) to keep the Service stable for everyone; sustained abuse may result in throttling, suspension, or termination.
No warranty on verdicts
deliverable verdict means our checks succeeded at the time of the request; it is not a guarantee the mailbox will accept mail in the future, that the recipient will read it, or that your message won't be filtered as spam. An unknown verdict means we could not get an answer; it is not evidence the address is bad. Mail server behavior, greylisting, and temporary outages are outside our control. THE SERVICE AND ITS OUTPUT ARE PROVIDED "AS IS," WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. WE DO NOT WARRANT THAT VERIFICATION RESULTS ARE ERROR-FREE OR THAT USE OF THE SERVICE WILL NOT RESULT IN YOUR OWN OUTBOUND EMAIL BEING FILTERED, BLOCKED, OR FLAGGED BY A THIRD-PARTY MAIL PROVIDER.
Limitation of liability
To the maximum extent permitted by law, CheckMX will not be liable for indirect, incidental, special, consequential, or punitive damages, or for any loss of revenue, deliverability reputation, or data arising from your use of, or inability to use, the Service. Our total liability for any claim relating to the Service is limited to the amount you paid us for the Service in the 3 months preceding the claim.
Termination
You may stop using the Service at any time. We may suspend or terminate access for violation of the acceptable-use terms above, non-payment, or if required by law. We'll make a reasonable effort to notify you first except in cases of active abuse.
Changes to these terms
We may update these terms as the Service evolves (for example, when real SMTP verification and paid checkout ship, see the pricing page for current status). We'll update the date at the top of this page when we do. Continued use after a change means you accept the updated terms.
Contact
Questions about these terms: hello@checkmx.dev.