What should the mail.debug=true option of javax.mail do?

Question

In the configuration properties of my javax.mail.Session I have set mail.debug=true, but for some reason, this doesn't add any new output to the application log.

I've set the log4f logging level to ALL log4j.rootLogger=ALL, stdout and yet... nothing.

Is it possible that the javax.mail debug output is written somewhere else? Sounds unlikely, but nevertheless I thought it worth asking.

Answer 1

It goes on console. Official FAQs

Answer 2

Setting log level of com.sun.mail.smtp to DEBUG worked on Wildfly(JBoss)