RSSMailingList is a free combination mailing list manager and RSS feed generator. It's made up of a few PHP scripts and a MySQL database. Your users can subscribe to whichever notification method they prefer and they will recieve the same content when you add it.
Version 1.0 is available here: rssmailinglist-1.0.zip
Installation instructions and descriptions of all the files can be found inside the README.txt file (also included in the download zip).
RSSMailingList sends out text-only emails, no HTML. Every email contains an automatic personalized unsubscribe URL at the bottom of it. It uses the server it's installed on to send out the emails, so your server account must be able to send out as many emails as you have email subscribers.
RSSMailingList is free for personal and commercial usage, with no restrictions.
Here's a demo installation. Sign up for the mailing list or subscribe to the RSS to get notified of any updates to RSSMailingList!
Support and Changes
RSSMailingList is a free PHP package and is intended for users that have experience with PHP/MySQL. If you're having trouble then you can email the creator at firstname.lastname@example.org and I might be able to help you. If you have any changes that you want to contribute back into RSSMailingList then please send them to me.