SMTP Test: Check Your SMTP Server and Email Sending Configuration
Test your SMTP server, verify ports and authentication, and detect issues affecting email sending and deliverability.
Results
- Free SMTP test
- Instant results
- No signup required
What does this SMTP test analyze?
Run a complete SMTP test and get a clear diagnosis of your server connectivity, configuration, and sending performance.
SMTP server connectivity
Verify that your SMTP server is reachable and responding.
Port and protocol check
Test ports (25, 465, 587) and encryption settings (SSL/TLS).
Authentication validation
Ensure credentials and login mechanisms are correctly configured.
Response time analysis
Measure server latency and performance during connection.
SMTP errors and failures
Detect timeouts, connection issues, and misconfigurations.
Sending reliability impact
How SMTP configuration affects delivery success and performance.
Common SMTP Server Examples
Here are standard SMTP configurations used by popular email providers.
Gmail SMTP
smtp.gmail.com (port 587)
Microsoft 365 SMTP
smtp.office365.com (port 587)
Yahoo SMTP
smtp.mail.yahoo.com (port 465)
Custom domain SMTP
smtp.yourdomain.com
Secure SMTP (SSL)
smtp.example.com (port 465)
TLS SMTP (recommended)
smtp.example.com (port 587)
How SMTP Works and Why It Matters
SMTP (Simple Mail Transfer Protocol) is the standard protocol used to send emails from one server to another.
When an email is sent, your system connects to an SMTP server, authenticates the sender, and transmits the message to the recipient’s mail server.
A properly configured SMTP server ensures reliable sending, while misconfigurations can lead to delays, failures, or blocked emails.
SMTP process includes:
Example:
mailX Related Email Authentication Tools
Check, validate, and improve the technical setup behind your email sending and deliverability.
Common SMTP Errors This Tool Detects
Connection failed
SMTP server is not reachable.
Port blocked
Firewall or ISP blocks SMTP traffic.
Authentication failed
Invalid username or password.
TLS/SSL misconfiguration
Encryption settings are incorrect or missing.
Slow server response
High latency impacts sending performance.
Timeout errors
Server does not respond within expected time.
SMTP, Email Sending & Deliverability Guides
What Is SMTP and How It Works?
SMTP is the protocol that email servers use to send, relay, and deliver messages across the internet.
How to Fix SMTP Errors?
SMTP errors are response codes that tell you exactly what went wrong when an email fails to deliver.
Email Deliverability: The Complete Guide to Reaching the Inbox (2026)
Email deliverability refers to the ability of your emails to reach your recipient’s primary inbox rather than being filtered into spam...
Free SMTP Test Tool to Check Email Sending Configuration
Use this SMTP test tool to verify your SMTP server, test connectivity, and detect issues that may prevent your emails from being sent successfully.
SMTP is the protocol responsible for sending emails. If your SMTP server is misconfigured, emails may fail to send, be delayed, or impact your deliverability.
This tool helps you test SMTP connectivity, validate server settings, and identify configuration errors before they affect your email performance.
SMTP Test Results
Connection Status
Connection successful / failed / timeout / unreachable
Server Details
SMTP host, port used, encryption type, and response time
Issues & Fixes
Detected problems & recommended fixes
Fix Your Email Deliverability with an Expert
Get a personalized audit of your SMTP setup, authentication, and email infrastructure. Identify what’s breaking your email sending and get clear, actionable fixes in a 30-minute session.