Welcome to SMTP Tester ("we", "us", or "the service"), accessible at smtptester.org. By accessing or using our website and testing tools, you agree to be bound by these Terms of Service ("Terms"). If you do not agree with these Terms, please do not use the service.
1. Description of Service
SMTP Tester is a free web-based utility designed to help developers, system administrators, and IT professionals test and verify Simple Mail Transfer Protocol (SMTP) server connectivity, TLS/STARTTLS negotiation, authentication mechanisms, and message submission.
The service performs real-time SMTP handshakes, displays protocol transcripts with sensitive credentials redacted, and provides diagnostic guidance.
2. Acceptable Use and Authorization
You agree to use SMTP Tester only for lawful purposes and in accordance with these Terms. Specifically, you agree that:
- Authorized Testing Only: You will only test SMTP servers, hostnames, IP addresses, and email accounts that you own, operate, or have received explicit, written permission from the owner to test.
- No Abuse or Denial of Service: You will not use the service to execute denial-of-service (DoS) attacks, flood mail servers, or bypass rate limits.
- No Spamming or Bulk Email: You will not use the message delivery feature to send unsolicited commercial email, phishing attempts, malware, or unlawful content.
- No Credential Harvesting: You will not use automated scripts or bots to attempt credential stuffing or brute-force authentication against third-party mail servers through our service.
- Respect Rate Limits: We enforce global and per-endpoint rate limits to ensure fair availability. Attempting to circumvent these limits via proxy rotation or automated requests is prohibited.
We reserve the right to block IP addresses, hosts, or networks that violate these acceptable use guidelines.
3. Privacy and Credentials Handling
Your privacy and security are foundational to SMTP Tester:
- No Credential Storage: We do not store, log, or persist the SMTP usernames or passwords you enter. Credentials are held in memory solely for the duration of the test connection and are immediately discarded upon completion or disconnection.
- Transcript Redaction: Authentication payloads and credentials are automatically redacted before transcripts are streamed to your browser or exported.
- Browser-Side Storage: Any saved connection profiles or preferences remain stored locally on your device in your browser's local storage.
For comprehensive information on our data practices, please review our Privacy Policy.
4. Availability and Modifications
The service is provided free of charge on an "as is" and "as available" basis. We strive for high availability but make no guarantee that the service will be uninterrupted, error-free, or continuously available.
We reserve the right to modify, suspend, or discontinue any aspect of the service, including features, rate limits, or diagnostic tools, at any time without prior notice or liability.
5. Disclaimer of Warranties
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, SMTP TESTER AND ITS OPERATORS DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, ACCURACY OF DIAGNOSTIC OUTPUT, AND NON-INFRINGEMENT.
SMTP diagnostics and error hints are provided for informational and troubleshooting purposes only. Successful testing through SMTP Tester does not guarantee inbox delivery, provider reputation, or delivery compliance with third-party email providers.
6. Limitation of Liability
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, IN NO EVENT SHALL SMTP TESTER, ITS MAINTAINERS, CONTRIBUTORS, OR AFFILIATES BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES, INCLUDING BUT NOT LIMITED TO LOSS OF DATA, LOSS OF BUSINESS, SERVER BLACKLISTING, OR DELIVERY FAILURES ARISING OUT OF OR IN CONNECTION WITH YOUR USE OF OR INABILITY TO USE THE SERVICE.
7. Third-Party Services and Links
Our website and documentation contain links to third-party services, mail providers, and external documentation (such as Google, Microsoft, AWS, SendGrid, and Cloudflare). We do not control, endorse, or assume responsibility for any third-party websites, software, or services.
8. Changes to These Terms
We may update or revise these Terms from time to time to reflect changes in our service, legal obligations, or operational practices. The "Last updated" date at the top of this page indicates when the latest revisions were made. Your continued use of SMTP Tester following the posting of revised Terms constitutes your acceptance of the changes.
9. Contact
If you have questions, concerns, or legal inquiries regarding these Terms of Service, please contact us at hello@smtptester.org or privacy@smtptester.org.