5.7.10: encryption needed
The server requires an encrypted connection (TLS) before this kind of login can happen, or a message that demands TLS could not be passed on securely.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.7.10
- Provider
- Standard SMTP codes
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
5.7.10 Encryption Needed
What it means
RFC 5248 registered X.7.10 from industry practice: the client tried an authentication mechanism, usually a plain-text one, that the server allows only over an encrypted connection, and the RFC associates it with reply code 523. The client can start TLS and try again. RFC 8689 (REQUIRETLS) gave the code a second use: when a message marked as requiring TLS cannot reach the next server over a TLS-protected session, the sending server returns it with 5.7.10. In both cases the cure is an encrypted path, either on the client's own connection or on the route to the recipient.
Common causes
- A client that tries to log in with a plain-text method before starting TLS.
- A mail client set to connect without encryption.
- A REQUIRETLS message whose next server could not set up a TLS-protected session.
How to fix it
- 01Turn on STARTTLS, or use the provider's implicit TLS port, in the client's outgoing server settings.
- 02Check the provider's documentation for the correct port and encryption setting.
- 03For a REQUIRETLS bounce, check whether the recipient's MX servers offer TLS, or resend without the requirement if the content allows it.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 538 5.7.11Encryption required for this login method.The chosen authentication method may only be used over an encrypted connection, and the current SMTP connection is not encrypted.
- 5.7.30REQUIRETLS not supported by the next server.The message was sent with a REQUIRETLS requirement, and none of the servers it had to go through next supports that requirement, so it was returned.
- 538Encryption required for this login method.The authentication method the client chose is only allowed over an encrypted connection, and this connection is not encrypted.
- 530Authentication required.The server requires the client to log in, or to start TLS, before it accepts this command, which usually means before it accepts any mail.
5.7.10 at other providers
Further reading
All 105 standard codesEvery code in the wikiPaste your own bounce