Attached is a package consisting of an auth module and related local en_utf8 translations for Moodle PLUS a plugin for Roundcube. The theory behind this module is that when a Moodle user logs in, the username and password is saved to a shared cookie, the password being encrypted by MCRYPT using a shared secret salt. When the user attempts to browse to the webmail client and specifies an action 'performsso' on the HTTP request (eg, http://webmail.stcuthberts.school.nz/?_task=mail&_action=performsso"), the roundcube plugin reads the shared cookie and attempts to decrypt the password and log in. The salt and cookie name need to be hard-configured in the roundcube mdlsso plugin in lines 20 and 17 of mdlsso.php respectively, and the plugin needs to be enabled in the Roundcube config. Details are in the INSTALL file in the distribution. The documentation may do with a little updating to improve readability, and a block may need to be created so that a link can be created from the Moodle auth plugin's configuration?