Docker Container SMTP Mail Server Integration with Appian Issue

Hi,

I'm trying to integrate docker container packaged mail server with Appian application by updating custom.properties and password.properties.

SMTP mail server currently integrated with Slack and works as expected(i.e. receiving slack notifications) when testing it separately using "curl" from CLI.

However, Trying to test SMTP mail server integration from Appian thru process model - Send Email Smart Serrice node. I could not receive any output / email and no error messages on docker log and Tomcat logs.

We've already turned on below DEBUG settings,

log4j.logger.com.appiancorp.process.runtime.activities.SendEmailActivity=DEBUG 

log4j.logger.com.appiancorp.ap2.mail=DEBUG

It seems Appian is not communicating with SMTP mail server as we could not see any entries on docker logs. Process Model Send Email smart service status is “unattended”, this has been initiated as per tomcat logs and no error messages as shown below.

2021-08-05 14:58:41,403 [Appian Work Item - 877 - execution00 : UnattendedJavaActivityRequest] DEBUG com.appiancorp.process.runtime.activities.SendEmailActivity - fromKey=processInitiator
2021-08-05 14:58:41,403 [Appian Work Item - 877 - execution00 : UnattendedJavaActivityRequest] DEBUG com.appiancorp.process.runtime.activities.SendEmailActivity - usingCustomSenderOption=false
2021-08-05 14:58:41,407 [Appian Work Item - 877 - execution00 : UnattendedJavaActivityRequest] DEBUG com.appiancorp.process.runtime.activities.SendEmailActivity - Sender Display Name: James Stanley
2021-08-05 14:58:41,407 [Appian Work Item - 877 - execution00 : UnattendedJavaActivityRequest] DEBUG com.appiancorp.process.runtime.activities.SendEmailActivity - Sender Option for [fromKey]: EmailOption [id=processInitiator, displayName=Process Initiator, emailValue=alerts@<domain name>, isExpression=false]
2021-08-05 14:58:41,412 [Appian Work Item - 877 - execution00 : UnattendedJavaActivityRequest] DEBUG com.appiancorp.process.runtime.activities.SendEmailActivity - Setting 'Sender' header to alerts@<domain name>
2021-08-05 15:07:27 INFO [ajp-nio-0.0.0.0-8009-exec-10] com.sun.jersey.server.impl.application.WebApplicationImpl._initiate Initiating Jersey application, version 'Jersey: 1.19.4 05/24/2017 03:20 PM'

custom.properties settings:

conf.mailhandler.ntf_sndr_addr=alerts@<Server Domain>

conf.mailhandler.email.domain=<Server Domain>

conf.mailhandler.mail.smtp.host=smtp.<domain name>:2525

conf.mailhandler.mail.smtp.auth=true

conf.mailhandler.mail.user=alerts@<Server Domain>

conf.mailhandler.mail.transport.protocol=smtp

conf.mailhandler.mail.smtp.starttls.enable=true

conf.mailhandler.mail.smtp.starttls.required=false

password is mentioned in password.properties file.

conf.password.SMTP=mypassword

We should at least get some appian log message saying “Could not connect to SMTP host” / “Email listener not configured “? It's weird that we could not see any SMTP connection related log messages…

Is there any way to check / test connection b/w docker container SMTP mail server and Appian is fine? I understand this relying on custom.properties, however I could not get any hint on tracing the mail server integration issue here. Any suggestions will be greatly appreciated. :) Thanks.