Australian companies spend AU$1.8 billion (US$1.85 billion) annually to send account bills and statements, according to a report written by Ries.

DPA is a consortium of three companies: Zumbox Software, which provides the software platform and two others, Computershare and Salmat. Those two companies already control about 85 percent of the time-sensitive financial digital mail sent, such as invoices and credit-card statements, Ries said.

Zumbox's platform, which is in use in the U.S., allows billers to send exact replicas of bills to customers to a secure online portal linked to their physical mailing address. It's free for consumers, with bulk mailers paying but spending less than sending physical bills.

Australia Post when it announced its competing Australia Post Digital Mailbox, but said it had been investigating the technology for years. But on Wednesday, Australia Post announced that it will use digital delivery system.

Similar to Zumbox, Volly is a web-based platform where vetted bulk mailers send communications to consumers who have opted in. Volly also incorporates a payment platform for pay bills.