I take it you reported the f#$%r to his ISP?
Where you able to get his IP from the email headers?
Reporting his ISP to spamcop is a good start ;D nothing like a few 1,000 angery customers who can't send email ;D ;D ;D
one last question, do you know if it was a member here? theres nothing like abit of a public flogging! hehe ;D