Troubleshooting Tip: How to troubleshoot Email Server configuration error 'Authentication Failed: Invalid username or password' in FortiSIEM

While configuring Email Server in FortiSIEM under Admin -> Settings -> System -> Email, the following error is observed after entering correct Username/password, Email Server IP/URL and port details.

Authentication failed: Invalid username or password

AppSvr logs shows exact errors while checking logs as below.

tail -f /opt/glassfish/domains/domain1/logs/phoenix.log

2025-11-17 15:04:32,081 [p: thread-pool-1; w: 59] ERROR com.ph.phoenix.service.notify.email.SmtpClientHelper - [PH_APPSERVER_NOTIFIER_ERROR]:[eventSeverity]=PHL_ERROR,[phEventCategory]=3,[procName]=AppServer,[phCustId]=0,[phLogDetail]=AuthenticationFailedException: 535 5.7.3 Authentication unsuccessful [MA5PR01CA0128.INDPRD01.PROD.OUTLOOK.COM 2025-11-17T09:34:49.124Z 08DE2522D0FE77B3]

tail -f /opt/glassfish/domains/domain1/logs/server.log

• Note down the exception AuthenticationFailedException: 535 5.7.3 Authentication unsuccessful
• This exception describes that SMTP Authentication may be disabled from Email Server for security reasons even though Username/Password is correct.
• Email Service providers such as Gmail/Microsoft Office365 disable SMTP authentication from other applications such as FortiSIEM.
• SMTP Authentication and related configuration needs to be enabled from Email Server to resolve such errors.
• Once the necessary configuration changes have been applied from Email server, Email Server configuration can be tested and saved successfully.

Related document:

Email Settings - FortiSIEM user guide