The ‘custom domain’ feature allows you to run Mail’ette completely from your own domain, making it completely seamless for your clients. With it enabled, all URL’s created by the system will be generated using a subdomain created on your domain name. You can set up the Custom Domain to run from an entirely new domain if you wish.
Example : http://preview.yourdomain.com
Sometimes it takes a little while to switch over, depending on your domain registrar and DNS, but you can send a test and should get back a completely customised Mail’ette page running off your domain.