Ismail

Does the same functionality as BuddyPress, emailing users who get mentioned in a bbPress topic or reply. The aim of this plugin is when to enable that feature when no BuddyPress is there. 
To do: – warn user about bbPress/BuddyPress presence

bbPress Mentions Email Notifications

Adds the @mentions to bbpress - really useful

Great plugin

Email bbPress topic/reply mentioned users, set custom email and some basic settings

wpyb

To prevent that usernames are publically visible, the username in the author’s permalink is replaced with the author’s ID. 
In case the page is invoked with the default permalink structure, it is displayed “Page not found”.
Additionally it is possible to modify the author base. It is recommended to make use of this plugin to change it, but it also works with other plugins that have the functionality to customize the author base.

Change Author Link Structure

To prevent that usernames are publically visible, the username in the author's permalink is replaced with the author's ID.

bbPress Mentions Email Notifications vs Change Author Link Structure