FeedBlitz users can subscribe to RSS feeds, and have the contents delivered as an email…publishers (bloggers) can also use this service as an email subscription for their blog.
Following in the steps of BlogBridge FeedBlitz users can now subscribe to Reading Lists, ie. they can subscribe to an OPML URL (that contains feeds), if feeds are added/deleted by the owner of this OPML URL, then it will reflect also in your subscription.
If you have a list of subscribers you can also create a local OPML file of your subscriber list…I think any type of list should have an OPML file, so you can apply it elsewhere.
Also to note is that FeedBlitz have enabled a subscriber number chicklet.