email notification with digest and comments?

I’m looking for a plugin that will let readers subscribe to be notified via email when either posts or COMMENTS are made to the blog as a whole, but that will also let them choose to have that notification be digested (sent once a day).
I’ve found some great resources that enable email notification but only of posts, not comments. None that I see handle the digest part.
I know that RSS handles that type of thing, but the target audience for this blog is NOT going to be receptive to using RSS or reading anything that they haven’t gotten notification of via email. (can you say “techno resistant”?) We’re trying to “ease” them into the world of blogging by hybridizing it with some listserv-type features (which they’re familiar with).
Any help will be greatly appreciated!
Karen