Addressing Senate estimates this morning, Deputy Secretary James Chisholm said Optus sent two emails about the outage on September 18 – the first at 2.45pm when it was detected, and the second seven minutes later when it was fixed — were sent to an old, out-of-date address.

The inbox wasn’t monitored, so it wasn’t until the next afternoon that the department found out about the outage.

“We have systems in place for notification. That requires information being sent to the right place,” Chisholm said.

“That email was not even sent to the right place.”

This was despite Optus using the correct email address before the outage.

“Optus had, indeed, regularly been sending outage notifications to the correct outage notification email address in all instances other than the incredibly significant outage of the 18th of September,” First Assistant Secretary Samual Grunhard said.

The hearing was told the telecommunications industry had been told which address to use, and that the correct one is publicly listed on the Australian Communications and Media Authority’s (ACMA) website.

9news.com.au has contacted Optus for comment.

It also coincided with a visit to parliament by Lawrence Wong, the prime minister of Singapore, the home of Optus’ parent company, Singtel.

Following a meeting with Prime Minister Anthony Albanese, Wong said he expected the companies to fully cooperate with the investigation into the outage.

“I understand fully the anger, frustration and outrage at what happened… I’ve extended my condolences to those impacted by the outage, including the family members and loved ones of those who lost their lives, which is tragic,” he told reporters.

“All I can do is to say, from a government’s perspective, we expect our companies to act responsibly.”

Optus had already faced heavy criticism for its handling of and response to the outage, particularly its communication about it.

The telco had initially told ACMA that it had only impacted 10 calls, and it wasn’t until the day after the outage, late on Friday, September 19, that the public was informed about the issue.

Rue also admitted Optus received at least five calls to its customer service line about the outage before it was fixed.