Create Mail Script

Right now members can currently login and under settings they can choose whether to be updated or not to be updated each time a new newsletter is in their inbox. The script now is poorly written and is using a cron job to tell it to send out 750 e-mails every 1/2 hour until it's complete. This takes a long time to send out to 8,000 or so members. This way also slows down my system and the MySQL ends up going into the red zone because it's using up all the system resources. I would like this reprogrammed so it sends out the e-mail notifier properly and does it in a timely manner! Maybe not use cron jobs? If possible I would like to send to all email addresses at the same time without slowing the system down. Other websites send out 50,000+ emails every day to their subscribers. How do they do it and my site can't even send out 8,000 e-mails? From my understanding the site should use PHPMail to send the e-mail notification and the exim should be configured properly! I do not understand any of this programming talk, but this is what my Hosting Provider has told me. I am on a VPS Server so I do not have a limit to how many emails I can send per hour. I am on the VZ1 plan over at [login to view URL] When you are done writing the script, I need to know the exact location on the server of the files and how everything works. The site is being upgraded in a few weeks and I would like the programmer to use this newly written script. Please also view the attached picture to understand what I am talking about when I say the MySQL reaches critical.