Inbound email fails with SMTP Response 530 5.7.1 Client was not authenticated

04/09/2020 10 13601

DESCRIPTION:

Inbound email fails with SMTP Response 530 5.7.1 Client was not authenticated

After enabling Anti Spam on the SonicWall device, when tried sending an email from one of the external email accounts; the email gets bounced back with an error message “530 5.7.1 Client was not authenticated”. If the Anti Spam is disabled then the email comes via SonicWall inbound without any problem.

CAUSE:

Anti-Spam service in SonicWall UTM appliance runs in a proxy mode and the error would be generated from the internal exchange or email Server.

RESOLUTION:

 Follow the steps listed below which describes the changes needed in the exchange or email Server to fix the issue.

• Open Exchange Mail Console (EMC).
• Navigate to Server Configuration > Hub Transport.
• Click on the properties of the default receive connector.
• Click on the Permission Groups tab.
• Enable the check box Anonymous users.
• Click on OK to apply the change.

Once the above change is applied, then the inbound email should come through fine without any issues.