---
title: What is SMTPS Port 465? | SendHQ
description: Technical explanation of SMTPS port 465, its use for implicit TLS encryption, and how it differs from STARTTLS on port 587.
canonical: https://sendhq.cc/terms/what-is-smtps
last-updated: 2026-08-26
---
# What is SMTPS Port 465?

SMTPS port 465 is a network port used for the Simple Mail Transfer Protocol Secure (SMTPS) to send emails using implicit TLS encryption. Unlike other ports that start as cleartext, port 465 requires a secure TLS handshake to be established before any SMTP commands are exchanged between the client and the server.

## Implicit TLS Mechanics

Port 465 utilizes implicit TLS, meaning the connection is encrypted from the very first packet. The client initiates a TLS handshake immediately upon connecting to the server. If the handshake fails or the server does not support TLS, the connection is dropped. This differs from explicit TLS, where a connection starts in plain text and is upgraded via the STARTTLS command.

## Port 465 vs Port 587

Port 587 is the standard port for mail submission using explicit TLS (STARTTLS). While port 465 was originally deprecated by IANA in favor of 587, it remains widely used by many legacy systems and modern providers. The primary technical difference is the timing of the encryption: port 465 encrypts before the SMTP session begins, while port 587 encrypts during the session.

## Security Implications

Using port 465 prevents the risk of cleartext command leakage that can occur during a failed STARTTLS upgrade on port 587. By enforcing encryption at the transport layer immediately, it ensures that authentication credentials and email content are never transmitted in the clear. Developers should ensure their client libraries are configured for SSL/TLS rather than STARTTLS when using this port.

## Implementation and Configuration

When configuring a mail client or application to use port 465, the SSL/TLS setting must be enabled. If you are troubleshooting connection timeouts, verify that your firewall allows outbound traffic on TCP port 465. You can use SendHQ free tools (https://sendhq.cc/tools) to verify other DNS related email configurations like SPF or DKIM to ensure your authenticated mail is accepted by receivers.

## Questions teams ask

**Is port 465 deprecated?**

While IANA previously reassigned it, RFC 8314 recommends implicit TLS on port 465 for submission to improve security over STARTTLS.

**Should I use port 465 or 587?**

Use port 465 for implicit TLS if your provider supports it. Use port 587 for explicit TLS (STARTTLS) as it is the official submission standard.

**Does port 465 require a password?**

The port handles the encryption layer; authentication (SMTP AUTH) is a separate step that usually occurs after the TLS tunnel is established.

## Primary sources

- [Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) — IANA
- [RFC 8314: Cleartext Considerations for Post-SMTP Email Protocols](https://www.rfc-editor.org/rfc/rfc8314) — RFC Editor
- [RFC 5321: Simple Mail Transfer Protocol](https://www.rfc-editor.org/rfc/rfc5321) — RFC Editor

## Continue learning

[smtp port](https://sendhq.cc/guides/smtp-port.md) [mail protocol smtp](https://sendhq.cc/guides/mail-protocol-smtp.md) [free smtp service](https://sendhq.cc/guides/free-smtp-service.md) [email deliverability](https://sendhq.cc/guides/email-deliverability.md)