Some advance usage of javamail and apache james smtp server... but I guess not much ppl will use this server, right? - http://cephas.net/blog/2006/06/09/using_apache_james_and_javamail_to_implement_variable_envelope_return_paths.html

Code sample of using auth required SMTP server - http://timarcher.com/?q=node/53

Properties to prevent infinite timeout for all socket operations, in Java mail - http://andreas.haufler.info/2014/06/javamail-can-be-evil-and-force-you-to.html