So you have a reseller account or your own dedicated server WHM/cPanel is installed - you have all the NS records for your domains pointed to the server - everything is working well, that is, until a customer happens to perform something like http://network-tools.com/nslook/ on their domain and see all the SOA information contains information about a different hosting company they didn't sign up with.
The easy fix:
1) Log into your WHM account
2) Enter DNS into the search box under the WHM logo
3) On the menu under the search box - select Edit DNS zone
4) Select the domain you would like to edit
5) Across the top of the domain information is the SOA information block.
6) In the field marked notifications.serversaustralia.com.au - change this to an email address of your choice. Just keep it in the same format, as above:
notifications.serversaustralia.com.au => firstname.lastname@example.org
so if your email is email@example.com enter it into the field as fred.test.com.au
7) Scroll to the bottom of the screen and click "Save"
Give the DNS time to propagate (upto 24 hours) everything should be displaying as you need.