Port 465 (SMTPS) — What It Is and How to Use It

Port 465 was initially designated for SMTPS (SMTP over SSL), providing implicit TLS/SSL encryption for sending email. While officially deprecated in favor of STARTTLS on port 587, some older systems and configurations may still utilize it. It's crucial for secure email transmission when implemented correctly.

Last updated: 2026-03-02

                Port Number
                465
            

Protocol SMTPS

Common Use Cases

Legacy systems requiring implicit SSL/TLS for SMTP
Specific email client configurations that haven't migrated to STARTTLS
Testing and debugging of older email server setups

Check if Port 465 is Open

netstat -tulnp | grep :465

Get-NetTCPConnection | Where-Object {$_.LocalPort -eq 465}

⚠️ Security Note: Using port 465 with outdated SSL/TLS protocols can expose email communications to vulnerabilities. Modern systems should prioritize STARTTLS on port 587 for enhanced security.

Related Ports

Frequently Asked Questions

Is port 465 dangerous to leave open?

Leaving port 465 open isn't inherently dangerous, but it's crucial to ensure the underlying SMTPS service is properly configured with strong encryption and authentication. If the service is outdated or misconfigured, it could be vulnerable to exploitation. Regularly audit and update the service to mitigate risks.

What service uses port 465?

The service that uses port 465 is SMTPS (SMTP over SSL/TLS), which is a method of encrypting SMTP traffic using SSL/TLS from the beginning of the connection. While deprecated, it's still found in older systems.