There are currently two e-mail web clients you can use through your browser.

NEOMAIL and HORDE
To access you web mail use the following URL

http://www.yourdomain.co.nz:2095 - the following screen will display asking for your user Name and Password
(note there is a colon : after the domain name)

You have a choice of two mail browser clients to choose from:-

Once you have select one of the above options, following instructions on the screen to setup your personalised webmail for the first time.

What is the difference between Horde and Neomail in the control panel?

Neomail is a simpler web based email client, where Horde includes extra features such as calendars and to-do lists.