550 Authentication is Required for Relay
If you are unable to send emails from your email client and receive the following error:
550 Authentication is Required for Relay
this usually indicates that the SMTP server requires authentication before allowing the email to be sent.
Cause
The error commonly occurs when SMTP Authentication is disabled or the email client is not using the correct SMTP authentication settings.
To resolve the issue, ensure that your email account is configured to authenticate with the SMTP server using the same email address and password used for the incoming mail server.
Enable SMTP Authentication
Microsoft Outlook
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Open Outlook and go to File → Account Settings → Account Settings.
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Select the affected email account and click Change.
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Open More Settings.
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Select the Outgoing Server tab.
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Enable My outgoing server (SMTP) requires authentication.
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Select Use same settings as my incoming mail server.
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Click OK and complete the account configuration.
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Restart Outlook and try sending the email again.
The exact menu names may vary depending on the Outlook version.
Other Email Clients
If you are using another email application, look for the Outgoing Mail Server (SMTP) or SMTP Authentication settings and make sure:
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SMTP authentication is enabled.
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The SMTP username is the full email address.
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The SMTP password is the correct mailbox password.
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The option to use the same credentials as the incoming mail server is enabled, where available.
Check SMTP Server and Port Settings
If SMTP authentication is already enabled and the problem continues, verify that the SMTP server name and port are correct for your hosting account.
Use the SMTP server, port, and security settings provided in cPanel under the email account's configuration settings. Make sure the SMTP port and encryption/security option match the settings provided in cPanel.
Note: A 550 Authentication is Required for Relay error generally means the SMTP server has rejected the message because the client has not successfully authenticated for mail relay.
