Mailing List app?

I am looking to create a mailing list app to try and help learn rails
plus it will be useful for a project that I am working on. I was
wondering if there is already one of these available to use as a guide?
Here is what I would like it to be able to do.

  1. subscribe page
  2. unsubscribe page
  3. a mass subscribe for the admin from csv list of emails
  4. send html emails to the list

any ideas or thoughts would be great.