Hello Nick,
You can access the webmail interfaces we offer by going to http://mail.yourdomain.com (replacing yourdomain.com with your actual domain) and selecting the IMP or SQWebMail links on the resulting page. If you wish to have a shortcut to the login pages accessed that way, you can bookmark those pages or possibly code a simple page which loads the login page inside a frame (useful for resellers who want to provide a friendlier URL than normally provided by the login page).