Newsletter using PHP and MySQL

Hiya, I have nearly finished a project I am working on, and completely forgot about having a newsletter service! Basically its a website, and on the registration page people opt in or out of the newsletter, and this is a field in the database. So either once a week, or randomly I want to be able to send a newsletter to about a million people (hopefully if all goes to plan). What I did envisage was running a PHP script through the command line, which got the first 100 or so which wanted the newsletter, then the next 100 etc, till all the users who wanted the newsletter got it. Now my Linux is a bit hazy, but I think I can run this low priority, because Iam not bothered if it will take a day or so to send them all. Sommat like this: 1- Read the first 100 emails that want the newsletter 2- Email them 3- If read 100, then go to 1 (but start from 100), if not quit So basically my questions are: 1- Is this the best way? Or should I use some mailing list software? I do want them to subsribe/unsubsribe through the website 2- Is there a point when the script would time out? I know in Apache, u can set a time limit for a script, but would a command line PHP script have the same problem? Ihave never run PHP through the command line. Thanks a lot, any advive or links would be great... Oh yeh nearly forgot, although it will be hosted on Linux, it will be tested on Windows 2k, so hopefully the mehtod would work for Win 2k but this is not necessary... Steve PS I have looked at a few archives, and searched the net but not seen anything that helpful...