About This Tool
The Online SMTP Tester is a dedicated utility to test SMTP email server connections. It connects to mail servers using TLS/SSL or a plain connection, verifies certificates, and authenticates using your provided credentials — without sending an actual email.
Enter your host, port, credentials, and encryption method, and the tool handles the connection, TLS negotiation, and authentication handshake for you — a quick way to confirm a mail account before wiring it into an application.
How to Use This Tool
Enter SMTP details
Fill in the host, port, username, password, and encryption method for your mail server.
Click "Test SMTP Connection"
The tool connects, negotiates encryption, and authenticates — without sending an email.
View the result
See an instant success or failure response, including connection latency.
Common Use Cases
Email Setup: Verify credentials before entering them into an email client or application configuration.
Diagnose SMTP Issues: Determine whether your host/port is blocked or your authentication parameters are failing.
Test Third-Party Services: Validate SendGrid, Mailgun, Amazon SES, or Google Workspace SMTP settings.
Save Setup Time: Avoid writing a terminal test script just to verify an SMTP login works.
Why Use This Tool
Comprehensive Testing
Supports common mail ports including 25, 465, and 587.
Protocol Specific
Tests STARTTLS negotiation and direct SSL wrappers natively.
Secure
Credentials are transient and never logged in our systems.
Detailed Output
Provides exact error messages directly from the mail server (e.g., auth failed, relay denied).