Yeah .. could just easily be ISP ... or even processor getting eaten up.

But, if you have 100 million emails ...they are most likely old or no good - in which case the bounce backs alone would freeze the application or freeze the machine. All while blacklisting your I.P. anyway ....haha

I wouldn't send spam from your desktop ... not a good idea. I HIGHLY doubt they are opt-ins.

I am not going to start a tut on here about how to do this. Just trust it isn't a good idea to do this without the right tools and knowing what your doing.

Best of luck