You are able to access the webmail from any browser just go to: https://www.yourdomain.com.au/webmail/ (where "yourdomain.com.au" is your actual domain name).
You will then be prompted for your full email address and password.
You will then be taken to a screen where you can manage your email account including setting up filters, managing space.
If you want to then view your inbox select the "roundcube" image at the top of the page
