When you have the email opened, In Netschape click
on "View" then "Headers" then "All"
This displays all the routing information.
Forward this to the ISP using their special abuse
id. As an example
abuse@seidata.com
The person there will notify the senders ISP of the
abuse, add blocks to your own ISPs system to stop further abuses.
If needed they can and will inform government or law
inforcement officials of problems.
At SEI Data the person in charge of the abuse desk
is Ron Schunk.