Terms of Service & Master Services Agreement

1. Corporate entity, binding agreement & scope

MailCheckup is owned and operated by Secuno LLC, a limited liability company organized under the laws of the State of Wyoming, USA, having its principal registered office at 30 N Gould St, Sheridan, WY 82801, USA (Executive Telephone: +1 (315) 961-7074; Legal Contact: legal@mailcheckup.net).

By creating an account on cp.mailcheckup.net, querying the MailCheckup REST API, provisioning an MCP server key, or uploading an email list for verification, you agree to be bound by these Terms of Service. If you represent an entity, you warrant that you possess full corporate authority to bind that entity to these Terms.

2. Account registration, security & API key governance

Customers must maintain accurate, current registration credentials. Workspace accounts utilize API secret keys prefixed with mck_. Keys are generated via cryptographically secure pseudo-random number generators (CSPRNG) and hashed at rest using the Argon2id key derivation function.

Customer is solely responsible for maintaining key confidentiality. API keys are revealed exactly once upon generation. You agree never to embed API keys into client-side code, public GitHub repositories, or untrusted browser runtimes. Compromised keys must be immediately revoked via the customer portal.

3. Verification engine, diagnostic methodology & limits

MailCheckup executes diagnostic deliverability checks adhering to RFC 5321 specifications. For each queried address, our engine performs syntax parsing, DNS MX resolution, disposable domain radix-tree matching (against 97,000+ domains refreshed every 6 hours), and a remote Port 25 SMTP diagnostic handshake (HELO, MAIL FROM, RCPT TO, QUIT).

Strict Deliverability Disclaimer: A "deliverable" or "valid" outcome confirms solely that the remote Mail Transfer Agent accepted the recipient mailbox during the socket handshake. MailCheckup does NOT warrant or guarantee that an email sent to a deliverable address will reach the recipient's primary inbox, avoid spam or quarantine filters, achieve any open rate, or remain active subsequent to the time of verification.

4. Credit economy, non-expiring packs & billing

Verification usage is measured in credits. A finished conclusive result (deliverable, undeliverable, catch-all, disposable, role account, mailbox full) consumes exactly one credit. In accordance with our $0 Free Unknown Policy, inconclusive checks (greylisted deferrals, connection timeouts, mail server unreachable, provider rate limits) are released free of charge and consume zero credits.

Credit Persistence: On-demand credit packs purchased through Stripe Checkout never expire. Monthly plan credits expire at the end of each paid billing cycle. As detailed in our 7-Day Voluntary Refund Policy, unconsumed credit pack balances are eligible for refund upon written request submitted within seven (7) calendar days of payment.

5. Customer representations, warranties & list provenance

Customer expressly represents and warrants that all email lists, recipient records, and addresses submitted for verification have been lawfully acquired in full compliance with all applicable data protection and anti-spam statutes, including the United States CAN-SPAM Act, the Canadian Anti-Spam Legislation (CASL), the European Union GDPR, and the UK PECR.

Customer covenants that it shall NOT submit addresses acquired via unauthorized web scraping, brute-force dictionary permutations, automated contact harvesters, or third-party unauthorized CD-ROM dumps. Customer warrants that it will not utilize MailCheckup to execute denial-of-service attacks or port 25 flooding against remote mail servers.

6. Proprietary rights, data ownership & zero resale

Customer retains 100% of all right, title, and intellectual property interest in all email lists, recipient names, custom metadata, and data files uploaded to MailCheckup. Secuno LLC claims zero ownership over customer verification inputs.

Ironclad Zero Resale Covenant: Secuno LLC covenants that it shall NEVER resell, license, broker, monetize, transfer, disclose, or aggregate Customer's uploaded email lists to any third party, data broker, lead generation vendor, or marketing firm. Customer lists are processed ephemerally in RAM and stored encrypted in AWS US-East strictly to provide verification reports to Customer.

7. Disclaimer of warranties & "AS IS" operation

EXCEPT AS EXPRESSLY SET FORTH HEREIN, THE SERVICES, REST APIS, BULK VERIFICATION TOOLS, AND DOCUMENTATION ARE PROVIDED STRICTLY "AS IS" AND "AS AVAILABLE". TO THE MAXIMUM EXTENT PERMITTED BY LAW, SECUNO LLC DISCLAIMS ALL WARRANTIES OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.

SECUNO LLC DOES NOT WARRANT THAT THE SERVICE WILL BE UNINTERRUPTED, ERROR-FREE, OR FREE OF TEMPORARY NETWORK DEFERRALS RESULTING FROM REMOTE THIRD-PARTY MAIL EXCHANGER RATE LIMITS OR FIREWALL POLICIES.

8. Limitation of liability & damages cap

IN NO EVENT SHALL SECUNO LLC, ITS AFFILIATES, OFFICERS, EMPLOYEES, OR AGENTS BE LIABLE TO CUSTOMER OR ANY THIRD PARTY FOR ANY INDIRECT, INCIDENTAL, CONSEQUENTIAL, SPECIAL, PUNITIVE, OR EXEMPLARY DAMAGES, INCLUDING LOSS OF PROFITS, LOSS OF REVENUE, LOSS OF DATA, REPUTATIONAL DAMAGE, OR BUSINESS INTERRUPTION, REGARDLESS OF THE THEORY OF LIABILITY (CONTRACT, TORT, NEGLIGENCE, STRICT LIABILITY, OR OTHERWISE).

12-Month Total Fee Cap: SECUNO LLC'S TOTAL AGGREGATE LIABILITY ARISING OUT OF OR RELATING TO THESE TERMS OR THE SERVICE SHALL IN NO EVENT EXCEED THE TOTAL FEES ACTUALLY PAID BY CUSTOMER TO SECUNO LLC DURING THE TWELVE (12) MONTH PERIOD IMMEDIATELY PRECEDING THE EVENT GIVING RISE TO LIABILITY.

9. Customer indemnification obligations

Customer agrees to defend, indemnify, and hold harmless Secuno LLC, its subsidiaries, affiliates, officers, directors, and employees from and against any third-party claims, liabilities, damages, losses, costs, and expenses (including reasonable attorneys' fees) arising out of or related to: (a) Customer's violation of these Terms; (b) Customer's breach of representations concerning lawful list acquisition; (c) Customer's transmission of unsolicited commercial communications (spam) violating CAN-SPAM, CASL, or GDPR; or (d) infringement of third-party privacy or intellectual property rights.

10. Term, suspension & termination rights

Secuno LLC reserves the right to immediately suspend or terminate Customer's API access, workspace credentials, or verification queue without prior notice if: (a) Customer breaches these Terms or our Acceptable Use Policy; (b) Secuno LLC detects anomalous verification patterns indicating dictionary scanning or Port 25 flood attacks; or (c) Customer fails to satisfy overdue invoices. Upon termination, unconsumed credits associated with terminated abusive accounts are forfeited.

11. Governing law, dispute resolution & jurisdiction

These Terms, and all claims arising out of or related to them or the Service, shall be governed by and construed in accordance with the laws of the State of Wyoming, USA, without giving effect to any principles of conflicts of law. The parties expressly exclude the application of the United Nations Convention on Contracts for the International Sale of Goods.

Any dispute, controversy, or claim arising out of or relating to this contract shall be submitted to the exclusive jurisdiction of the state courts located in Sheridan County, Wyoming, or the United States District Court for the District of Wyoming. The parties hereby consent to personal jurisdiction in such courts.

The table below summarizes our contractual governance framework:

12. Frequently asked terms questions