Im’ OK with Mark : +1
It exist “bbPress Post via Mail” but it is not a very intuitive plugin and very simple.
Some days ago, i wanted to create this sort of plugin, but i’m not a crack in PHP and mostly, with developpement for WordPress 🙁
My idea was simple : if a new topic is create in forum, all people that can access to this forum receive the message write in the topic. People can answer by replying by mail and this reply come as a new reply in the forum.
If someone want to create a new topic by mail, he write a new mail to a specific address mail and also add before the mail title a specific tag as “(new)le titre de mon sujet” for exemple…
In the admin page, we can use specific POP3/IMAP and SMTP server… and also may be specify who can use this functionaly (user / group / role / etc…)