The new SpamAssassin version separates rules as a core component. To update rules, a new sa-update command is required. The behavior was already an option in version 3.2.x, but has now become the standard thanks to some positive feedback.

The new release also improves the plugin for DomainKeys Identified Mail (DKIM) that now supports Author Domain Signing Practices (ADSP) and many other signatures. The DKIM plugin is activated with all new installations, while the old DomainKeys plugin was retired.

Developers also improved IPv6 support. The new time_limit configuration option, defaulted at 300 seconds, attempts to gracefully terminate the checking after the given time limit and returns the results so far. Further details are in the comprehensive release notes. Special notes are available for users wishing to upgrade.

The SpamAssassin project, under the Apache Software Foundation umbrella for over six years, provides version 3.3.0 of its software in source code downloads in various binary formats, under Apache License 2.0.