In the past I have used Gammadyne Mailer, but now days I doubt that would work with most ISPs. Most have a cap on how many messages they let you send, which is mine caps at 2,000 per day. Your best bet is to use a company like Constant Contact or OnLetterhead to do a blast. Those companies do a decent job at staying off the black lists and will usually let you send as many emails as you need per day. Please make sure your have a 100% opt-in list for everyone's benefit.