In osDate, there is a mass email sender, I sent an email to everyone that was registered (approximately 10k members at the time), the website did take about 5-10 minutes before it started fuctioning, everyone got the emails, and my server didn't say much. osDate is in php so you can definetly extract the mailer, and make a db with all your contacts and do it that way. Not sure about your server, but I was using bluehost at the time, and there really good, moved up to a few dedicated servers