By comparison, Postini intercepted 1,400 e-mails infected with Sobig.F on its first day, and 3.5 million the second, Scott Petry, vice president of products and engineering at Postini, said.
The increased traffic from Mydoom hurt overall Internet performance, Keynote Systems Inc. said. The company said its tracking index showed that the Internet at noon Pacific time was 8 percent to 10 percent slower than normal for a Tuesday. Performance, however, was back to normal by 2:30 p.m.
The Mydoom attack appears aimed, in part, at setting up computers for a Feb. 1 attack against the web server of the SCO Group Inc. The company has been the target of several attacks over the last 10 months, with the latest in December taking down the company's server for more than a day.
While not proven, SCO may have been targeted because of its legal challenge of the open-source operating system Linux, which the company claims contains its copyrighted code. SCO's lawsuits have angered the Linux community and its supporters. Conversely, Linux enthusiasts say the virus may have been assembled for the purpose of defaming Linux developers.
On Tuesday, SCO offered a $250,000 reward for the arrest and conviction of the Mydoom virus author.