Internet insecurity

Today I received an email that appeared to be from Internet.Filtering@dbcde.gov.au, with the subject line Cyber-safety and internet service provider filtering [SEC=UNCLASSIFIED]. I was immediately suspicious that this was a spam email, because:

1. The main message content was in an attachment to the email (which I did not open).
2. The only email address given was a "no-reply" address.
3. The email was not addressed to me personally, nor was there any indication why I had received it. For example, I have recently signed some petitions to the government about internet filtering, but this email did not say, "You are receiving this email because you signed a petition about internet filtering" or some other such explanation.

This does not improve my trust in the government's plans for internet filtering, not one little bit. Either they have somehow had their email hijacked by a spammer, or they are spamming me! You would think that the Department of Broadband, Communications and the Digital Economy would know how to send an email securely....