After installing the plugin, and submitting a test comment to check the enhanced emails, I got a headers already sent error. I found that this was due to extra whitespace at the end of the
action_links.php file in the plugin. I would recommend just deleting the
?> and any extra blanks lines at the end of all the plugin files to fix the problem.
Other than that, this plugin rocks and I'm glad they are working on getting it into core for 3.3!