In recent versions of jForum there is a pop mail API available for that. AFAIK, the code if fairly stable, but there are no admin screens for it and limited documentation. So, you have to figure it out from the code. There are several
thread in the forums about people who have gotten this to work.
See the net.jforum.api.integration.mail.pop package.
The basic methodology is that POPJobStarter sets up a Quartz scheduled job. POPListener is the actual job code. This uses the information in the jforum_mail_integration table to map forums to pop addresses.
There is also some filtering to verify that there is a matching user id for the sender, etc.
[originally posted on jforum.net by monroe]