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SMTP Tester

Understand what SMTP testing involves and learn about the key checks that ensure your email server is properly configured.

Sign up for 25 free searches per month no credit card required.

// how it works

How to Use SMTP Tester

  1. 01

    Enter SMTP host

    Type your domain name into the input field to identify the mail server configuration.

  2. 02

    Test connection

    Click Analyze to review all SMTP checks including MX records, SPF, DKIM, DMARC, and TLS.

  3. 03

    View configuration

    Get a detailed overview of each check with explanations of what a full SMTP test verifies.

// features

Why Use SMTP Tester

  • TLS/SSL Testing

    Verifies STARTTLS support, certificate validity, TLS version, and cipher strength for secure email transit.

  • Authentication Verification

    Checks SPF, DKIM, and DMARC records to ensure your domain email authentication is properly configured.

  • Port Scanning

    Tests connectivity on standard SMTP ports including 25, 465, and 587 for submission and relay.

  • Connection Diagnostics

    Analyzes MX records, EHLO handshake, and server response codes to identify connectivity issues.

  • Response Code Analysis

    Interprets SMTP response codes like 220, 250, and 550 to diagnose server configuration problems.

  • Privacy Focused

    All configuration analysis runs in your browser. No credentials or sensitive data are transmitted.

// use cases

Who Uses SMTP Tester

  • DevOps Engineers

    Verify mail server configuration after deployment or migration to ensure all authentication records are correct.

  • Email Admins

    Diagnose deliverability issues by checking MX records, SPF alignment, DKIM signatures, and DMARC policies.

  • Developers

    Debug transactional email setup by verifying SMTP connectivity, TLS support, and authentication configuration.

  • IT Support

    Troubleshoot email sending failures by identifying missing DNS records or misconfigured mail server settings.

// faq

Frequently asked questions

Still have questions? Visit the help center

// quick start

Make your first call in a minute

Free account, real API key, the same endpoints Enterprise customers use.

  1. 1Create a free account25 searches a month. No card.
  2. 2Copy your key and secretFrom API keys in the dashboard.
  3. 3Call the APIPaste the request; the answer is JSON.
Get free API keyRead the docs
curl "https://api.tomba.io/v1/email-finder?domain=piedpiper.com&first_name=Richard&last_name=Hendricks" \
  -H "X-Tomba-Key: $TOMBA_API_KEY" \
  -H "X-Tomba-Secret: $TOMBA_SECRET_KEY"
Response
200 OK· 1 search credit
{
  "data": {
    "email": "richard@piedpiper.com",
    "first_name": "Richard",
    "last_name": "Hendricks",
    "full_name": "Richard Hendricks",
    "website_url": "piedpiper.com",
    "company": "Pied Piper",
    "pattern": "{first}",
    "department": "executive",
    "type": "personal",
    "position": "CEO",
    "country": "US",
    "gender": "male",
    "twitter": null,
    "linkedin": "https://www.linkedin.com/in/richard-hendricks",
    "score": 100,
    "accept_all": false,
    "phone_number": true,
    "verification": {
      "date": "2025-01-15T10:32:00+01:00",
      "status": "valid"
    },
    "sources": [
      {
        "uri": "https://piedpiper.com/blog/engineering",
        "website_url": "piedpiper.com",
        "extracted_on": "2024-06-01T09:14:07+01:00",
        "last_seen_on": "2025-01-10T17:02:44+01:00",
        "still_on_page": true
      }
    ],
    "phone_data": []
  }
}