Careful with your choice of words. Do you mean "send them so much email their server MIGHT crash", or do you mean "hack their network and sabotage their system, in violation of State law that makes computer sabotage a felony." ????
I suggest that you clarify that.
Now Freep the PC bastard who came up with this.
Correction to above post of mine...EMail there server to the point where it MIGHT just get the message across...God forbid it doesn't have the capacity for 100,000 emails.