Seems like a non-unique non-targeted offer code, but perhaps only useful for new customers.
Free delivery only applies to purchases of wine, champagne, spirits & ciders. This free delivery offer is available from 02 March 2015 to 08 March 2015 and only available for Standard delivery to Metropolitan areas as specified on danmurphys.com.au/deliveryareas. Offer excludes delivery to Tasmania and purchases containing beer and RTDs. Customers must be registered and signed in to danmurphys.com.au to redeem this offer. This offer can only be redeemed once per customer. To redeem your free delivery, enter promo code DMWEL0315 in the payments section during checkout. Dan Murphy's does not deliver to Northern Territory and parts of Queensland and Western Australia.
Holden is doing free delivery (except for cars)