Java Mail Server
Apache James as mail server.
It seems the project is useful however there are really limited resources.
The example on the link below somehow worked and I am able to use it;
Looking for more example and tutorials.
As I find the resources, I will be editing here.
The video is really a good motivation to use James as a mail server because there is completed reference project
Video Link - Reference Project
I could not make it work on AWS. It is hard to set up a mail server on AWS. The defaults ports are closed for security.
Better to use Amazon Simple Email Service instead.
Or use Webmail.
For paid mail service from AWS is that Amazon Workmail.