Online SMTP Test

Test your SMTP server connection and email sending functionality instantly.

Home Online SMTP Test
Our free SMTP Test tool allows you to check the connection to your mail server (SMTP relay). Verify your host, port, and security settings to ensure your email sending is working correctly and troubleshoot common delivery failures. Test your SMTP server now!

Quick Setup - Common Providers

Click a provider to automatically fill in SMTP settings

SMTP Server Configuration

SMTP server hostname or IP address

Common ports: 25, 465 (SSL), 587 (TLS)

Encryption method (TLS recommended) - auto-selects port

SMTP authentication username (optional)

SMTP authentication password (optional - never stored or logged)

Sender email address

Test recipient email address

Maximum time to wait for connection (5-60 seconds)

Disable for self-signed certificates

Note: Disabling SSL verification reduces security. Only use for testing with trusted servers.

Security Verification

To prevent automated abuse, please verify you're human. This tool is rate-limited to 3 attempts per hour.

Simple verification (No external tracking)

Understanding SMTP Configuration

What is SMTP?

SMTP (Simple Mail Transfer Protocol) is the standard protocol for sending emails across the internet. It's used by email clients and applications to send outgoing mail through an email server.

Handles outgoing email delivery
Requires authentication for security
Supports encryption (TLS/SSL)

SMTP Ports Explained

Port 25
Default/unencrypted - Often blocked by ISPs
Port 465
SSL encryption - Implicit TLS from start
Port 587 Recommended
TLS encryption - Modern standard, best compatibility

Encryption Methods

TLS (Transport Layer Security)

Modern encryption standard. Starts unencrypted then upgrades to encrypted connection (STARTTLS).

SSL (Secure Sockets Layer)

Older encryption method. Connection is encrypted from the start. Still widely supported.

None

⚠️ Unencrypted - Not recommended. Credentials sent in plain text.

Provider Tips

Gmail: Requires App Password (not regular password). Enable 2FA first, then create App Password in Google Account settings.
Yahoo: Also requires App Password. Generate one at account.yahoo.com → Security.
Office 365: Use your full email as username and regular password (unless MFA enabled).
SendGrid/Mailgun: Use API key as password. Find it in your provider's dashboard.
  1. 1 Enter Server Details: Input the SMTP Hostname (e.g., `smtp.gmail.com`), Port (e.g., `587`), and your Authentication Credentials (username/password).
  2. 2 Specify Emails: Enter a Sender Email and a Recipient Email address.
  3. 3 Run Test: Click "Test SMTP Connection".
  4. 4 View Status: The tool attempts a full handshake and login, reporting if the connection succeeded, failed, or if the test email was sent successfully.

What is SMTP?

SMTP (Simple Mail Transfer Protocol) is the primary protocol used to send emails between mail servers. Testing it verifies your ability to send outgoing mail.

What are the common SMTP ports?

The most common ports are 25 (unencrypted), 465 (SMTPS/SSL), and 587 (Submission/TLS), with 587 being the modern standard.

What causes an SMTP connection failure?

Failure is usually caused by incorrect host/port details, invalid login credentials, or a firewall blocking the outbound connection from your network.

Email Setup Troubleshooting

Example Keyword: test smtp server connection
Verify configuration settings when setting up an email client, application, or notification service.

Firewall Diagnostics

Example Keyword: check if smtp port is blocked
Test if your network's security settings are unintentionally preventing outgoing email traffic.

Credential Verification

Example Keyword: test email username and password
Confirm that the authentication details for your mail server are correct and functional.

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