Revert last commit; passing by reference like that causes deprecation PHP notices in PHP4. It is the responsibility of the receiving plugin to accept the args by reference if it intends to change its value.

functions/plugin.php

@@ -80,7 +80,7 @@ function do_hook($name, &$args) {
         foreach ($squirrelmail_plugin_hooks[$name] as $plugin_name => $function) {
             use_plugin($plugin_name);
             if (function_exists($function)) {
-                $ret = $function(&$args, $ret);
+                $ret = $function($args, $ret);
             }
         }
     }