530 Authentication Required while setting up Mail Server

Hi,

We recently set-up a on-premise installation Appian 21.2 which run on a Docker Container. While configuring the mail server setup we were unable to send email using the Send Email Smart Service.

When we looked at the 

tomcat-stdOut.log we found 
2021-08-24 06:39:00,391 [Appian Work Item - 1 - execution00 : UnattendedJavaActivityRequest] ERROR com.appiancorp.ap2.mail.Mail - Could not send mail via smtpout.secureserver.net:465 to 
2021-08-24 06:39:00,394 [Appian Work Item - 1 - execution00 : UnattendedJavaActivityRequest] ERROR com.appiancorp.process.runtime.activities.SendEmailActivity - com.sun.mail.smtp.SMTPSendFailedException: 530 authentication required

com.sun.mail.smtp.SMTPSendFailedException: 530 authentication required

 at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:2108)
 at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:1609)
 at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1117)
 at com.appiancorp.ap2.mail.Mail.sendMessage(Mail.java:407)
 at com.appiancorp.ap2.mail.Mail.sendMessage(Mail.java:278)
 at com.appiancorp.ap2.mail.Emailer.send(Emailer.java:131)
 at com.appiancorp.ap2.mail.Emailer.send(Emailer.java:126)
 at com.appiancorp.process.runtime.activities.SendEmailActivity.execute(SendEmailActivity.java:416)
 at com.appiancorp.suiteapi.process.framework.AbstractActivity.perform(AbstractActivity.java:104)
 at com.appiancorp.process.runtime.framework.LegacyActivityExecutor$2.call(LegacyActivityExecutor.java:90)
 at com.appiancorp.process.runtime.framework.LegacyActivityExecutor$2.call(LegacyActivityExecutor.java:87)
 at com.appiancorp.common.ContextClassLoaderSwitcher.runInContext(ContextClassLoaderSwitcher.java:23)
 at com.appiancorp.process.runtime.framework.LegacyActivityExecutor.execute(LegacyActivityExecutor.java:87)
 at com.appiancorp.process.engine.UnattendedJavaActivityRequest.execute(UnattendedJavaActivityRequest.java:88)
 at com.appiancorp.process.engine.UnattendedJavaActivityRequestResponseCreator.getJavaActivityResultResponse(UnattendedJavaActivityRequestResponseCreator.java:21)
 at com.appiancorp.process.engine.UnattendedJavaActivityRequest.getJavaActivityResultResponse(UnattendedJavaActivityRequest.java:67)
 at com.appiancorp.process.engine.UnattendedJavaActivityRequest.execute0(UnattendedJavaActivityRequest.java:55)
 at com.appiancorp.common.persistence.data.AppianDataUserContextProvider.executeWithConsistentDataReads(AppianDataUserContextProvider.java:116)
 at com.appiancorp.process.engine.ProcessContinuationRequest.executeOuter(ProcessContinuationRequest.java:68)
 at com.appiancorp.process.engine.ContinuationRequest.execute(ContinuationRequest.java:123)
 at com.appiancorp.process.workpoller.UnattendedRequestHandlerBean.onMessage(UnattendedRequestHandlerBean.java:36)
 at com.appiancorp.process.workpoller.WorkItem.run(WorkItem.java:94)
 at org.springframework.jca.work.SimpleTaskWorkManager$DelegatingWorkAdapter.run(SimpleTaskWorkManager.java:239)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
 at java.lang.Thread.run(Thread.java:748)


Our custom.properties
conf.suite.SCHEME=https
conf.suite.SERVER_AND_PORT=appian.xxxx.com
conf.data.APPIAN_DATA_SOURCE=jdbc/AppianPrimaryDS
conf.mailhandler.mail.smtp.host=smtpout.secureserver.net:465
conf.mailhandler.mail.smtp.auth=true
conf.mailhandler.mail.transport.protocol=smtps
#conf.mailhandler.mail.smtp.starttls.enable=true
#conf.mailhandler.mail.smtp.starttls.required=true
conf.mailhandler.mail.user=xxxxx.xxxxx.com
conf.mailhandler.ntf_sndr_addr=xxxxx.xxxxx.com
conf.mailhandler.poller.EmailHandlerBean.debug=true


Thank you in advance.