What to do
- Enable authentication and STARTTLS in the client or relay settings.
How it appears in a bounce
530 Authentication requiredPaste the full bounce into the decoder — it finds every code and recipient and says what to check.
SMTP 530 Authentication required
The server requires authentication or TLS before it accepts the command.
530
- Class
- 5xx · Permanent failure
- Retried?
- No, the message bounces
- Defined in
- RFC 4954