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AuthenticationFailedException 535 5.7.3 Error When Sending SMTP Emails from QRadar SOAR and Outbound Email Behind Load Balancer

Troubleshooting


Problem

SMTP email notifications sent for IBM Security QRadar SOAR and emails sent from the Outbound Email application stopped working with no changes made to SOAR or application configurations.

Symptom

Emails were not sent from SOAR nor the Outbound Email application.

Document Location

Worldwide

[{"Type":"MASTER","Line of Business":{"code":"LOB77","label":"Automation Platform"},"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSA230","label":"IBM Security QRadar SOAR"},"ARM Category":[{"code":"a8m0z0000001jmrAAA","label":"Resilient Core-\u003ENotifications"}],"ARM Case Number":"TS016068418","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All Versions"}]

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Document Information

Modified date:
23 June 2026

UID

ibm17149323