For Telstra customers.
I have received an email from Admin Support no-Reply@ telstra.com. Note the hyphen and upper case R in their address. They told me that I will lose access to my mail box if I don't click on a link and agree to their revised terms and policy. I contacted Telstra who confirmed the email is a scam. They also said Telstra will never ask a customer to click on a link. So be careful.