Apparently some people missed the memo. The www prefix is no longer considered mandatory. Yet every now and then I encounter a site that fails to resolve when I type in the URL without the www prefix.
Back in the early days of the web it was just one service amongst many and it was reasonable to assume that you needed to specify which server handled web traffic. These days web traffic is the first class citizen of the InterBlag (and like most first class citizens looks very respectable but has rough edges you don't talk about in polite company). Giving it precedence is expected. Also www is really annoying to pronounce.
Therefore DHL Australia please fix this oversight and I'll say no more about it.