SMTP Port 465: Implicit TLS Email Submission

What SMTP port 465 means

Port 465 is registered as submissions: message submission over TLS. With implicit TLS, the TLS handshake begins as soon as the connection opens. Only after that encrypted session is established does the client authenticate and submit the message.

This is different from ordinary server-to-server SMTP delivery on port 25. The current Internet guidance is documented in RFC 8314.

Using port 465 with AuthSMTP

AuthSMTP accepts authenticated submission on port 465 using implicit TLS. In an application that offers separate SSL/TLS and STARTTLS choices, select SSL/TLS.

Use the exact SMTP hostname and credentials shown in your AuthSMTP Control Panel. The hostname is normally mail.authsmtp.com; do not substitute an IP address because certificate validation depends on the hostname.

For application-specific screens, see the AuthSMTP setup guides. If a connection succeeds but mail is rejected, follow the troubleshooting guide to check credentials, account status and authorised sender addresses.

Troubleshoot port 465

1. Confirm the security mode is SSL/TLS or implicit TLS, not STARTTLS.
2. Use the AuthSMTP hostname supplied to your account rather than its current IP address.
3. Re-enter the AuthSMTP username and password exactly; both are case-sensitive.
4. If the connection times out before a TLS session is established, test whether the network permits outbound port 465.
5. If your software cannot use implicit TLS, use port 587 with STARTTLS instead.

A successful port test only confirms that a connection can be opened. It does not validate the account password, sender authorisation or the application configuration.

Compare SMTP submission ports

Port 25 is primarily used for mail-server delivery and is frequently restricted on access networks. For an email application or website submitting mail to AuthSMTP, prefer 587 with STARTTLS or 465 with implicit TLS; use 2525 with STARTTLS when an alternative is needed.