Hello all,
While having many bug fixes and improvements, version 1.5 still had many problems, some of which were fundamental design issues. Therefore, the entire plugin has been re-written and version 2.0 is now in beta testing. Note that you'll also need a copy of the Server Settings Backend plugin (available from the SquirrelMail website) as well as one of the filter application sub-plugins (one for both Maildrop and Procmail are available here). Please refer to the plugin documentation in the docs directory of your download for more details.