What causes a 'relaying denied' error when sending emails, and how can I diagnose the issue?

The 'Relaying Denied' error arises when a mail server lacks authorization to send emails on behalf of a domain, often due to misconfigurations, authentication issues, or restrictive relay policies. These problems can include a failing destination domain, broken DNS, incorrect MX records, or the server being configured to prevent unauthorized relaying. To diagnose, verify MX records, ensure proper authentication (SMTP, SPF, DKIM), confirm the sending server's IP is whitelisted if necessary, and manually test delivery. Proper configuration, authentication, and explicit permission for relaying are key to resolving the error.

The 'Relaying Denied' error typically indicates that the mail server you're using is not authorized to send emails on behalf of your domain to the recipient's domain. Common causes include incorrect SMTP settings, lack of proper authentication, the server being blocked by the recipient's mail server, or the server not being configured to relay emails for external domains. Diagnosing the issue involves checking mail server configurations, verifying MX records, ensuring proper authentication (SMTP, SPF, DKIM), and confirming that the sending server's IP address is whitelisted if required. Misconfigurations or security measures to prevent spam often trigger this error.

The 'Relaying Denied' error commonly arises when a mail server attempts to send email on behalf of a domain without proper authorization. This can be due to issues with the destination domain, such as a dead domain, broken DNS, or service migration problems. It may also occur if the receiving server doesn't recognize itself as the final destination for the email and incorrectly assumes the sender is attempting to use it as a smarthost for relaying. Diagnosing the problem involves manually inspecting MX records and testing delivery to each MX server, verifying proper authentication, and confirming the server is configured to relay email for the domain.

The 'Relaying Denied' error stems from a lack of authorization for the sending mail server to relay emails on behalf of a domain. Documentation across various platforms (cPanel, Exim, Microsoft Exchange, Postfix, Sendmail) highlights that this issue arises due to factors such as incorrect MX records, authentication failures, misconfigured relay settings, or restrictive anti-relay policies. Resolving this typically involves ensuring proper authentication, configuring relay settings to allow specific IP addresses or networks, and verifying that the server is explicitly permitted to relay mail to the intended destination.