Fighting the spam

• spammers' lists
• SMPT sniffing
• users lists from broken computers
• subscription/unsubscription to advertising mailing lists

• do not unsubscribe unless you subscribed
• complain:
• abuse@domain
• SOA record with DNS - nslookup
• postmaster, root, administartor accounts
• whois records
  
• router owners - traceroute

Filters

• Handled at the SMTP server level
• Based on keyword match

• System-wide filters: against viruses, worms
• User filters:
• through mail forwarding (.forward) -> filter application (procmail)
• user supplied configuration file containing criteria