need ability to send email

I have a login area on this site already at [login to view URL] the login and registration works and info is stored in mysql, I need the ability to send email to all emails in the database and this ability only available to a certain login(admin), i see it happening like this, admin logs in, there is a button there that says "prepare email" they click it it pops up a screen that has "click to send to all users" check box and also a place to enter an email address and a subject field and a body to type a message and a button to add an attachment then of course the send button. Also once a user has logged in (any user) the login on top left would dissappear and say "user name is logged in" thanks, Brian