How to debug mail subsystem in docker

[mirak]

Hi,

I deployed the process services 2.0.0 in docker and configured email. Unfortunately, I get the error  java.net.SocketTimeoutException: Read timed out (error below).

Email configuration:

email.enabled = true
email.host = <mail_server_hostname>
email.port = 25
email.useCredentials = false
email.username =
email.password =
email.ssl = false
email.tls = false
email.base.url = https: // <server_hostname> / activity-app
email.from.default=noreply@alfresco.cz
email.from.default.name = ActivitiBMPN
email.feedback.default=noreply@alfresco.cz

The same configuration in the content services works smoothly (tested via the administration console). Telnet (<mail_server_hostname> 25) and ping to postfix mail server from the inside process container works well. 

Please advise how to debug this behavior.  How to set up debug logging for emails in case of docker container?

Thank you!

12:28:47 [http-nio-8080-exec-7] ERROR com.activiti.rest.exception.RestExceptionHandlerAdvice  - Internal error: 
org.activiti.engine.ActivitiException: Could not send e-mail in execution 12508
        at org.activiti.engine.impl.bpmn.behavior.MailActivityBehavior.handleException(MailActivityBehavior.java:410)
        at org.activiti.engine.impl.bpmn.behavior.MailActivityBehavior.execute(MailActivityBehavior.java:106)
        at org.activiti.engine.impl.agenda.ContinueProcessOperation.executeActivityBehavior(ContinueProcessOperation.java:226)
        at org.activiti.engine.impl.agenda.ContinueProcessOperation.executeSynchronous(ContinueProcessOperation.java:160)
        at org.activiti.engine.impl.agenda.ContinueProcessOperation.continueThroughFlowNode(ContinueProcessOperation.java:117)
        at org.activiti.engine.impl.agenda.ContinueProcessOperation.run(ContinueProcessOperation.java:82)
...
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: org.apache.commons.mail.EmailException: Sending the email to the following server failed : <mail_server_hostname>:25
        at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1469)
        at org.apache.commons.mail.Email.send(Email.java:1496)
        at org.activiti.engine.impl.bpmn.behavior.MailActivityBehavior.execute(MailActivityBehavior.java:101)
        ... 165 common frames omitted
Caused by: javax.mail.MessagingException: Exception reading response
        at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:2369)
        at com.sun.mail.smtp.SMTPTransport.close(SMTPTransport.java:1353)
        at javax.mail.Transport.send0(Transport.java:257)
        at javax.mail.Transport.send(Transport.java:124)
        at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1459)
        ... 167 common frames omitted
Caused by: java.net.SocketTimeoutException: Read timed out
        at java.base/java.net.SocketInputStream.socketRead0(Native Method)
        at java.base/java.net.SocketInputStream.socketRead(SocketInputStream.java:115)
        at java.base/java.net.SocketInputStream.read(SocketInputStream.java:168)
        at java.base/java.net.SocketInputStream.read(SocketInputStream.java:140)
        at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:124)
        at java.base/java.io.BufferedInputStream.fill(BufferedInputStream.java:252)
        at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:271)
        at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:92)
        at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:2349)
        ... 171 common frames omitted