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SMTP Checker
Test email servers, verify SMTP configuration, check blacklist status, and validate email deliverability with comprehensive analysis and security checks.
Checking SMTP server...
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Email Deliverability Score
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out of 100SMTP Statistics
Server Status & Connectivity
Connection Details
Quick Actions
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Why FileReadyNow
Test Your Mail Server and Diagnose Delivery Problems
Enter an email, domain, or SMTP hostname and find out if your mail server is reachable and properly configured.
Server Connectivity Check
Connects directly to your SMTP server and reports whether it is reachable and responding on the port you specify.
Blacklist Detection
Scans your server IP against known email blacklists that spam filters check. If your IP is listed, email will not reach the inbox.
All Standard Ports
Tests ports 25, 587, and 465 so you can confirm which ports your server is listening on and whether TLS is working correctly.
Security and TLS Check
Verifies TLS and STARTTLS support so you can confirm that encrypted connections are working the way your mail client expects.
MX Record Lookup
Looks up the MX records for your domain so you can verify that incoming mail is routed to the correct server.
No Account Required
Enter your server details and check. No signup, no software to install, and no limit on how many tests you run.
Email delivery failures are frustrating to diagnose because they can stem from several different points in the chain — the sending server, the port configuration, authentication settings, or a blacklist entry. The SMTP Checker from FileReadyNow tests your mail server directly, verifying connectivity, checking the ports your server responds on, and scanning for blacklist status, so you can pinpoint the problem without combing through server logs manually.
What This Tool Does
Enter an email address, domain, or SMTP server hostname and the tool connects to the server and runs a series of checks depending on the mode you select. Quick check verifies basic connectivity and server response. Comprehensive analysis tests the full mail server configuration including banner, EHLO response, and supported features. Security and blacklist mode checks whether the server or its IP appears on known email blacklists that could be causing delivery failures.
Supported Ports
The checker supports all standard SMTP ports:
- Port 25: Standard SMTP, used for server-to-server mail transfer
- Port 587: Submission port with STARTTLS, the recommended port for authenticated sending
- Port 465: SMTPS with implicit SSL, used by some providers for secure sending
- Port 2525: An alternative submission port used when port 587 is blocked by ISPs
- Custom port: Enter any port number for non-standard configurations
Common Use Cases
- Email Delivery Troubleshooting: Diagnose why emails are not being delivered by checking whether the SMTP server is reachable and responding correctly on the expected port.
- Blacklist Monitoring: Check whether your mail server's IP address appears on any spam blacklists that could be causing your emails to be rejected or marked as junk.
- New Server Validation: After setting up a new mail server or changing SMTP configuration, confirm the server is reachable and responding correctly before sending live emails.
- Third-Party SMTP Testing: Verify that a transactional email service such as SendGrid, Mailgun, or Amazon SES is correctly configured and reachable from your domain.
- Port Connectivity Check: Determine which SMTP ports your hosting provider or network allows, especially in environments where certain ports are blocked by firewalls or ISPs.
What to Expect from the Results
Results show the server's response at each stage of the SMTP handshake, including the server banner, supported authentication methods, and TLS availability. Blacklist results show which lists were checked and whether the server IP appears on any of them. If a blacklist entry is found, the result includes information to help you start the delisting process with the relevant provider.
Step by Step
How to Use SMTP Checker
Enter email address, domain, or SMTP server hostname.
Select port and check mode (Quick, Comprehensive, or Security).
View connectivity, security analysis, and deliverability recommendations.
Frequently Asked Questions
An SMTP Checker tests your mail server’s connectivity and verifies whether it can send and receive emails properly.
Testing helps diagnose email delivery failures, authentication issues, and incorrect server configurations.
No. The tool is beginner-friendly — just enter your SMTP server details to start testing.
Yes, it checks login credentials, port configuration, and server response codes.
Yes, your server details are only used for real-time tests and are not stored.