Ts
Tools

SMTP Test Tool – Free Online Mail Server Checker

Looking to test your SMTP server? Our free SMTP Test Tool helps you instantly check mail server connectivity, verify SMTP configurations, and troubleshoot email delivery problems. In addition, this online tool makes it simple for developers, sysadmins, and marketers to identify SMTP issues and ensure reliable email sending.

SMTP Server Configuration

Not connected

Connection Log

// SMTP connection log will appear here

Test Email

Email Log

// Email sending log will appear here

What is SMTP?

SMTP stands for Simple Mail Transfer Protocol, the standard protocol used for sending emails over the internet. Every email you send relies on an SMTP server to deliver the message to its destination. If your SMTP server is misconfigured, emails may fail to send, bounce back, or land in spam.

Why Use an SMTP Test Tool?

  • ✅ Emails are sent successfully without errors
  • ✅ Correct username, password, and authentication settings
  • ✅ No firewall or port blocking issues
  • ✅ Better inbox delivery rates (avoid spam/junk folders)

How to Use Our Free SMTP Test Tool

  1. Enter your SMTP server address (e.g., smtp.gmail.com).
  2. Provide the port number (25, 465, or 587).
  3. Add your username and password (if required).
  4. Click “Test Connection”.
  5. The tool will verify the connection and show results in seconds.

Key Features

  • ⚡ Instant results – check in under 5 seconds
  • 🔒 Secure testing – SSL/TLS supported
  • 📧 Email delivery simulation – verify end-to-end delivery
  • 🌍 Works with Gmail, Outlook, Zoho & custom servers
  • 💻 100% web-based – no installation required

Common SMTP Ports

  • Port 25 is the default SMTP relay; this port most of the cases blocked by ISPs. Port 465  Commonly used for secure SMTP over SSL. Port 587  The recommended choice for modern email sending with TLS support.

Troubleshooting SMTP Errors

  • ❌ Authentication failed – wrong username or password
  • ❌ Connection timed out – port blocked or firewall issue
  • ❌ Relay denied – server not allowing outgoing mail
  • ❌ Invalid hostname – wrong SMTP server address

Who Should Use an SMTP Test Tool?

This tool is designed for:

  • Developers – test email functionality in apps/websites
  • System administrators – verify company mail servers
  • Email marketers – ensure campaigns are delivered successfully
  • Businesses – reduce downtime and prevent lost emails

FAQs

How do I test my SMTP server?

Enter the server address, port, and credentials into our tool to instantly verify connectivity and authentication.

What is the best SMTP port to use?

Experts recommend Port 587 for secure TLS email delivery. ISPs often block Port 25; In addition, Port 465 remains a common choice.

Can I test Gmail SMTP with this tool?

Yes, use smtp.gmail.com with port 465 or 587 along with your Gmail credentials or App Password.

Why is my SMTP test failing?

Common issues include wrong credentials, blocked ports, or incorrect server addresses. The tool provides error messages to guide you.

Is this SMTP Test Tool free?

Yes, it’s 100% free and unlimited for all users.

Conclusion

SMTP is the backbone of email communication, and testing it regularly prevents downtime. With our free SMTP Test Tool, you can check server settings, verify connectivity, and ensure smooth email delivery. Start testing now to make sure your emails always reach the inbox, Learn more about how SMTP tester tool works. If you also need to test API responses, try our Mock API Generator tool, which works seamlessly alongside SMTP testing.