I would recommend using your email client to create a "group" which contains users you can email the information to.

If that's not what you're looking for and you actually want a 'database' I recommend MS Access for a simple database. You would need some sort of way to create an automated messaging system using that data though?

My company http://www.highconversions.com create a web based interface so you could have a contact management system online from which you could send out mass emails.