I’ve been researching this problem to no avail for sometime. We use the (very old) SpamAssassin plugin (http://squirrelmail.org/plugin_view.php?id=146) with our Squirrelmail. This plugin serves us well in terms of ease of use and we can connect it easily to our mail server spamassassin. The only issue that any time a user makes a change (like adding an email to the blacklist/whitelist), all prior changes are overwritten. In the README, there is a note that this was a bug but resolved.
Does anyone have any exp with this plugin and resolved this issue? Or is there an older thread regarding this plugin/issue that someone could point me to? Thanks for any help you guys can offer.