Hi there,
This is a shameless plug but I'm developing a service called relatebase.com which allows you to do all of these things. It's OK to store the newsletters in a database, but probably a text file emailed to the person will be the best (as an attachment).
However, is the newsletter also going to be achrived as an article somewhere? Will there be hyperlinks on it? If so, then please store it in a database so it can function for articles.
And, are you going to use any mail merge code in it so you get "dear John, dear sally, dear Joe" etc.??? based on their record in the database? My product does this.
Be happy to give you a demonstration of this and set you up as a beta tester. If you like it would could talk further. You can PM me or reply on the post either way.
Sincerely,
Sam Fullman