A spokesperson for the telco confirmed the increased traffic had caused some customers to experience 'Re-authentication errors' when checking their e-mail. The error causes e-mail clients such as Outlook to prompt users to re-enter their login details.
"To alleviate any further occurrences," the spokesperson said, "Optus is undertaking a software and mail server upgrade over the next two weeks."
"Optus will upgrade the firmware that maintains the customers' connection to the networks and add more servers to increase capacity."
The virus problems come some six weeks after Telstra BigPond acknowledged the operation of its domain name servers had slowed to a crawl due to excessive amounts of bogus requests generated by Trojan-infected customer PCs.
At the time Telstra said it would address the problem by boosting the capacity of its servers, as well as disconnecting particularly troublesome customers from its network until they removed the malware from their machines.