Hi Christian,
Yes we do have the documentation that can help serve as your guide to setup this email posting feature.
Link: http://stackideas.com/docs/easydiscuss/administrators/configuration/setting-up-email-parser

While setting up Email Parser, do take note that there is a known issue in the current version of EasyDiscuss affecting the setup process. The fix will be included in the next release of EasyDiscuss. However, if you need to setup email parser now, kindly download the fix file that I have attached here. You can replace the file at: JoomlaFolder\administrator\components\com_easydiscuss\views\settings\view.ajax.php