{"id":157,"date":"2011-11-24T10:29:00","date_gmt":"2011-11-24T10:29:00","guid":{"rendered":"http:\/\/pheonixsolutions.com\/?p=157"},"modified":"2026-05-08T17:54:39","modified_gmt":"2026-05-08T12:24:39","slug":"telnet-to-secured-port-or-ssl-port-465-or-933-or-995","status":"publish","type":"post","link":"https:\/\/pheonixsolutions.com\/blog\/telnet-to-secured-port-or-ssl-port-465-or-933-or-995\/","title":{"rendered":"Telnet to secured port or SSL port 465 or 933 or 995"},"content":{"rendered":"

Introduction<\/h3>\n\n\n

Secure email communication is essential for protecting sensitive data and ensuring reliable mail delivery. Mail servers commonly use SSL\/TLS encryption on specific ports to provide secure connections for SMTP, IMAP, and POP3 services. When users experience issues sending or receiving emails, one of the first troubleshooting steps is to verify whether these SSL ports are open and functioning properly.<\/p>\n\n\n\n

The openssl s_client<\/code> command is a powerful and simple tool that allows system administrators and hosting users to test secure mail ports directly from the command line. By using this command, you can confirm whether the mail server is responding correctly, whether SSL certificates are properly installed, and whether firewall or service-related issues are blocking the connection.<\/p>\n\n\n\n

In this guide, we will learn how to check the status of commonly used secure mail ports \u2014 465<\/code> (SMTP SSL), 993<\/code> (IMAP SSL), and 995<\/code> (POP3 SSL) \u2014 using OpenSSL commands.<\/p>\n\n\n\n

Why SSL Ports Matter<\/h3>\n\n\n\n

Secure mail ports encrypt the connection between the email client and the mail server. This prevents unauthorized access to sensitive information such as usernames, passwords, and email content.<\/p>\n\n\n\n

Common SSL\/TLS mail ports include:<\/p>\n\n\n\n

Service<\/th>Port<\/th>Purpose<\/th><\/tr><\/thead>
SMTP SSL<\/td>465<\/td>Sending emails securely<\/td><\/tr>
IMAP SSL<\/td>993<\/td>Receiving and managing emails securely<\/td><\/tr>
POP3 SSL<\/td>995<\/td>Downloading emails securely<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

If any of these ports are blocked, closed, or misconfigured, users may experience connection failures in email applications like Outlook, Thunderbird, or mobile mail apps.<\/p>\n\n\n\n

Commands to Check SSL Ports<\/h3>\n\n\n\n

Use the following commands in your terminal or SSH session to verify whether the SSL ports are working correctly.<\/p>\n\n\n\n

Check SMTP SSL Port (465)<\/h3>\n\n\n\n
openssl s_client -quiet -connect mail.thespirals.com:465<\/code><\/pre>\n\n\n\n
Purpose<\/h3>\n\n\n\n
This command checks whether the SMTP SSL service is active and accepting secure connections on port 465<\/code>.<\/p>\n\n\n\n
Successful Connection<\/h3>\n\n\n\n
If the port is working, you will see output similar to:<\/p>\n\n\n\n
CONNECTED(00000003)depth=2 ...220 mail.thespirals.com ESMTP<\/code><\/pre>\n\n\n\n
Failed Connection<\/h3>\n\n\n\n
If the port is blocked or unavailable, you may see errors such as:<\/p>\n\n\n\n
Connection refusedconnect:errno=111<\/code><\/pre>\n\n\n\n
or<\/p>\n\n\n\n
Connection timed out<\/code><\/pre>\n\n\n\n
Check IMAP SSL Port (993)<\/h3>\n\n\n\n
openssl s_client -quiet -connect mail.thespirals.com:993<\/code><\/pre>\n\n\n\n
Purpose<\/h3>\n\n\n\n
This command verifies whether the IMAP secure service is running properly on port 993<\/code>.<\/p>\n\n\n\n
Successful Response Example<\/h3>\n\n\n\n
CONNECTED(00000003)* OK IMAP4 ready<\/code><\/pre>\n\n\n\n
This confirms that the IMAP SSL service is active and functioning.<\/p>\n\n\n\n
Check POP3 SSL Port (995)<\/h3>\n\n\n\n
openssl s_client -quiet -connect mail.thespirals.com:995<\/code><\/pre>\n\n\n\n
Purpose<\/h3>\n\n\n\n
This command tests the POP3 secure mail service on port 995<\/code>.<\/p>\n\n\n\n
Successful Response Example<\/h3>\n\n\n\n
CONNECTED(00000003)+OK POP3 server ready<\/code><\/pre>\n\n\n\n
This indicates that the POP3 SSL port is working correctly.<\/p>\n\n\n\n
Additional Troubleshooting Tips<\/h3>\n\n\n\n
If the ports are not working properly, try the following:<\/p>\n\n\n\n
1. Check Firewall Rules<\/h3>\n\n\n\n
Ensure the required ports are open in the server firewall.<\/p>\n\n\n\n
Example for CSF firewall:<\/p>\n\n\n\n
465,993,995<\/code><\/pre>\n\n\n\n
2. Verify Mail Services<\/h3>\n\n\n\n
Check whether the mail services are running.<\/p>\n\n\n\n
For Exim:<\/p>\n\n\n\n
service exim status<\/code><\/pre>\n\n\n\n
For Dovecot:<\/p>\n\n\n\n
service dovecot status<\/code><\/pre>\n\n\n\n
3. Restart Mail Services<\/h3>\n\n\n\n
service exim restartservice dovecot restart<\/code><\/pre>\n\n\n\n
4. Confirm DNS Records<\/h3>\n\n\n\n
Make sure the mail hostname points to the correct server IP address.<\/p>\n\n\n\n
Example:<\/p>\n\n\n\n
mail.thespirals.com<\/code><\/pre>\n\n\n\n
Benefits of Using OpenSSL for Port Testing<\/h3>\n\n\n\n