Web interfaces to SpamAssassin
webuserprefs http://sourceforge.net/projects/webuserprefs/ This PHP front-end support web-based administration of both file-based and SQL installations, and a number of authentication options. Detailed configuration directions are available.
Maia Mailguard is a web-based interface and management system for the popular amavisd-new e-mail scanner and SpamAssassin. Written in Perl and PHP, Maia Mailguard gives end-users control over how their mail is processed by virus scanners and spam filters, while giving mail administrators the power to configure site-wide defaults and limits.
vMail.Admin is a web-based interface and management system for Postfix and SpamAssassin servers using SQL for storage. Written in PHP and Perl, vMail.Admin gives administrators control over global, per-domain and/or per-user settings while providing the same control to end users to manage their own SpamAssassin settings. Administrators are not limited to the default SpamAssassin options available with vMail.Admin because vMail.Admin gives administrators the power to add and/or remove any valid SpamAssassin option.
Webmin, an Open Source web-based system administration tool, includes a complete web interface for SpamAssassin. It can also manage procmail delivery rules as they relate to SpamAssassin. Usermin, a webmail (among other things) client based on Webmin, includes a report spam interface to sa-learn.
WebCFG is an easy-to-install easy-to-use platform independent generic web front end for editing local/remote based text files (e.g. system configuration files simply in your web browser - there is no need for shell commands or Unix editors anymore. After modification is done, WebCFG executes local / remote commands/scripts forcing processing the new configuration (e.g. restart / reload a dependant service). Injecting special comment-tags like '# @WC tab / radiobuttons / combobox / textbox /...' to the text file will optimize and beautify the presentation in the web frontend for you or your customers. WebCFG includes an example for SpamAssassin managing white- and blacklists.
php-sa-mysql2 http://mail.limelyte.net/downloads/standalone3.0.tgz. For a Demo of php-sa-mysql2 see http://mail.limelyte.net/webspam/ user test <at> nougen.com, pass test. Notes: php-sa-mysql2 requires register_globals = On, a rewrite is in process.
For Squirrel Mail
There are numerous front ends to Spam Assassin for SquirrelMail, which can all be found at http://squirrelmail.org/plugins_category.php?category_id=3
user-prefs file generator
Michael Moncur's spamconfig.php: http://www.yrex.com/spam/spamconfig.php. This generates a file suitable for download, rather than being a UI you can install on your server directly.