What I am looking for is a way for a user (not admin) to send a comment via email to a post on the blog site.
For example, say I create an email with the subject “voting” which is a category on my site. The plugin would then search the user database to see if the email address was in the database. If so, then the plugin would allow the comment to be installed as a comment.
Thus, the comment via email from a user to a post would look just the user logged in into the site and used the “Leave a Reply” method.