According to Microsoft, e-mails and attachments sent or received by any of Hotmail's 187 million Web mail customers will be scanned in real time by Trend Micro's antivirus software beginning Monday.
Hotmail's antivirus service was previously provided by McAfee and the reason for the change is unclear. However, Martin Hoffman, chief executive of Ninemsn, which operates Hotmail in Australia and is half owned by Microsoft, said in a statement that Hotmail will be able to provide a "safer online experience" using Trend Micro's products because they provide "deeper antivirus protection."
"Ninemsn is focused on providing a safer online experience for our Australian customers...We're pleased to work with Trend Micro, to provide deeper antivirus protection for our Hotmail customers," Hoffman said.
Dominic Finnegan, Ninemsn's director of ad products and pre-sales, said in response to e-mailed questions from ZDNet Australia: "We are constantly evaluating the needs of our customers as well as our business needs and feel that offering customers a variety of computing experiences further enhances and helps with their online protection.
"Trend has a proven track record and (it) made technical and business sense for us to work with them," Finnegan.
Steve Chang, chairman and founder of Trend Micro, which is best known for its PC-cillin Internet Security product, said in a statement that Trend Micro's vision is to make it safe for people to exchange digital information.
"This belief is behind everything we do for every customer we serve. We are thrilled to extend this to millions more," Chang said.
McAfee was unavailable for comment.
Munir Kotadia of ZDNet Australia reported from Sydney.