view the full headers, report the email (and headers) as a forward to email@example.com
often times if its a legit hotmail address, the spammer will have their account closed. ive been successful in doing so on quite a few occasions
if theyre not hotmail, do a search on google for a free ip tracer, view the headers of the email and look for the 123.456.78 looking number, trace it...
and whatever the last @ispnamehere.com is, copy firstname.lastname@example.org or email@example.com and forward the spam to them.