I mimic the Linux whois client. The IP address from the SPAM falls into a range of IPs assigned to a server. One server is chosen and whois query is performed to gather the information. If a whois entry has an "abuse-mailbox" record, that is the only email I report too. Otherwise, I send the abuse complaint to all emails in the entry.
If all that does not produce an email, I start using other servers:
The viewer will not contact the Internet. The spammer can not validate your email. The option is on the lower left hand corner of the Messages tab. Its tooltip says "Block remote images."