Admin Digest: Stopping Spam with Linux - page 2
Fret not! If your best efforts to block spam at the receiving end fail, Linux can still help you!
To complain back to the source of the mail you can look up the people that run the spam site with the whois command. Just use the left hand side of the address as input.
You'll get a listing of the registrant's address, city, state, phone number, etc. There is also usually a 'Technical Contact' section. Might be time to call or send an email to that contact. They may not even be aware of a spam problem.
Figuring out the 'upstream' Internet providers to the spam site can be done by using the traceroute command. Traceroute shows all the hops needed to get to a certain Internet address. For example type:
nslookup and dig
If traceroute and whois can't seem to find the right-hand side part of the email address, then nslookup or dig may be able to find you a good address you can use related to the mystery address. Please refer to the online documentation for more details.