Almost all email applications have an option to add a footer to your messages, it's not rude at all to give a link to your blog with each mail you send, but don't expect anyone to search their bookmarks for you.
This would make the comments more interesting, the idea of the group was to show off your blog and to create s conversation with you about blogging. You understand that your comment means a lot to me now.
If you subscribe to my comments by mail or rss you can track the postings I make that are most interesting to visitors and have at least 1 comment.
If you have any problems adding a footer to your email just ask away. If you don't want to use email for whatever reason you can still post a reply or start a new topic, no need for registration, can even post anonymous.