Spoofed/Forged Email  
   
   http://www.ja.net/CERT/CERT-CC/tech_tips/email_spoofing

Anti-spam information  
   Information, tools and techniques for fighting spam
   http://www.ja.net/CERT/JANET-CERT/anti-spam.html

Email bombing and Spam  
   General overview of problems associated with electronic mail bombing and email spamming. It includes information that will help you respond to and recover from this activity.
   http://www.ja.net/CERT/CERT-CC/tech_tips/email_bombing_spamming

Using check_* in sendmail 8.8  
   sendmail 8.8: using the check_* rules to prohibit unauthorized relaying through your sendmail server and to reject UBE from well known addresses
   http://www.informatik.uni-kiel.de/~ca/email/check.html

The Antispam Home Page  
   Instructions to automatically filter your e-mail, defend your site from exploitation by the spammers
   http://www.arachnoid.com/lutusp/antispam.html

Configuring a spam-resistant Sendmail  
   How to configure sendmail to reject spamming messages (from Computer Bits magazine)
   http://www.computerbits.com/archive/1998/0900/lan9809.html

How spam is sent  
   Explanation of the mechanics of spam from Computer Bits magazine.
   http://www.computerbits.com/archive/1998/0500/lan9805.html

Installing, and spamming, Sendmail 8.9  
   Features in Sendmail 8.9 to help reducing spamming messages
   http://www.computerbits.com/archive/1998/0700/lan9807.html

Sendmail spam filters  
   Sendmail resources from filtering spam (from Computer Bits magazine)
   http://www.computerbits.com/archive/1998/0800/lan9808.html

Will deleting spam soon become illegal?  
   The first of a series of articles on SPAM from Computer Bits magazine.
   http://www.computerbits.com/archive/1998/0400/lan9804.html

Disabling Relaying  
   List of M4 directives that will allow control of the relaying behavior in sendmail's master configuration (.mc) file, and therefore prevent spammers from using your site to relay their messages
   http://www-wsg.cso.uiuc.edu/sendmail/tutorial/anti-spam/no-relaying.html

The Spam Series - Email  
   A series telling everything about the Internet nuisance, spam, from your About.com Guide.
   http://email.about.com/internet/email/library/series/blspam_series.htm

Blocking Mailed Spam  
   This article discusses several alternatives available to sites that want to block mailed spam.
   http://www.spam.cl.cam.ac.uk/spam/