There are several stand alone Bulk Email software systems that can be run for this, which include options such as poMMo (no longer supported, but still viable), and several others both open-source, free, and for sale.
Considering the double opt-in, I am leaning toward using my own software but wanted the opinion of you Warriors as to what would be the best option. So to that end I am taking a poll "Use a Bulk Mail Service?" or "Use a Bulk Mail Software".
Thanks for your responses!