| Anti-Spam Configuration Control: Instructions for configuring Sendmail to prevent relaying and reject spam. |
| Anti-spam information: Information, tools and techniques for fighting spam |
| Blocking Mailed Spam: This article discusses several alternatives available to sites that want to block mailed spam. |
| Kai's SpamShield: Sendmail add-on that provides rate control and volume limits for Unix-based mail servers. Can stop spam from ISP's own customers, and mail bombers. |
| milter-regex: milter-regex is a sendmail milter plugin that allows to reject or discard mail based on regular expressions matching SMTP envelope parameters and mail headers and body. |
| milter.org: A blog focused on sendmail milter API. |
| The Antispam Home Page: Instructions to automatically filter your e-mail, defend your site from exploitation by the spammers |
| The Spam Series - Email: A series telling everything about the Internet nuisance, spam, from your About.com Guide. |
| 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 |
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