SMTP relay denied
This SMTP connection is not authorized to forward this mail.
What to do now
- Check that SMTP authentication succeeded.
- Check that you are using the correct SMTP server and submission port.
- If you operate the server, inspect relay destinations and accepted-domain settings.
Representative reply
550 5.7.1 Relay access denied
Retry decision
Retry after correcting authentication or accepted-domain policy.
Why it happens
Authentication or accepted-destination policy may prevent forwarding.
Typical stage
RCPT TO
- CONNECT
- EHLO
- MAIL FROM
- RCPT TO
- DATA
- DELIVERY
Stages vary by server. Confirm the actual stage from the complete reply and session logs.
What is SMTP Reply Code?Open only the explanations you need
Three-digit server reply: 4xx is transient, 5xx permanent. Read the complete text to investigate the cause.
What is Enhanced Status Code?Open only the explanations you need
An extended status such as 5.1.1. Server wording and usage may vary.
What is RCPT TO?Open only the explanations you need
SMTP command identifying a recipient.
What is SMTP Relay?Open only the explanations you need
Forwarding mail to another destination, governed by authentication and permission policies.
Check directly
- Check that SMTP authentication succeeded.
- Check that you are using the correct SMTP server and submission port.
- If you operate the server, inspect relay destinations and accepted-domain settings.
If you operate or diagnose the mail server, the tools below can help with these checks.
Cautions
Observed DSNs do not map one-to-one to causes. The stage shown is typical; confirm it with the full reply and actual logs.
Similar reply wording and observed status codes
isn't allowed relayrelaying deniedrelay access deniedrelay not permittedunable to relay recipient in non-accepted domain
Observed DSNs: 4.5.1, 5.7.1, 4.7.1, 5.1.3, 5.7.54