Email List Sign-Up Plugin

I’m looking for something pretty simple (I think) to gather e-mail addresses.

What I would like is a plugin that is a simple for where a user can enter in an email address that would be sent to a webmaster so they can be added to a subscription list for a newsletter. I am handling the list of email addresses from there, so I don’t need much automated. I just want to have a way for people to say “Yes, add me to this list” and, ideally, use the same plugin for people that want to opt out later.