Mailing form contents to multiple, selectable recipients

Hello!! I have a political website that I would like to create a page so that a person can send e-mails to all of the Reps and Sens or only a few or just one. There will be upwards of 150 at full capacity being sent each time. I am not sure how to do this. Should I use the mail() mail function and somehow create an array on the fly?? I am going to use the following in the webpage for the actual e-mail addresses: <select multiple> <option value=email.address1@somewhere.com>Name</option> <option value=email.address2@somewhere.com>Name</option> <option value=email.address3@somewhere.com>Name</option> <option value=email.address4@somewhere.com>Name</option> </select> So that a user can select all or some or all of the addresses. I also need to add some function for the user being able to choose whether to use his own text or a pre-written message. Can I put something like $name in the body of the message so that the e-mail can be personalized?? If someone could answer a few questions for me I would appreciate it very much!! Thanks, Jeremy