Why do I receive virus email from people at LPL whose computers are not infected?

LPL email addresses are contained in the email address books of thousands, if not millions, of computers worldwide. When a worm infects a random machine in the world, it harvests all of the email addresses stored on that machine and launches email messages to and from those addresses, forging the From: address. Human recipients tend to infer that these messages were sent by the user listed in the From: line, from the forged sender's computer. In reality, these messages could've originated on any computer in the world that has an address book that contains the actual recipient's and forged sender's addresses.

So, whenever a worm infects a computer (anywhere in the world) that contains an address book that contains LPL addresses, someone at LPL might receive forged worm email and might have their address used to forge worm email to other people. Companies, universities, and private parties worldwide are vulnerable to this problem and are contending with it. Given the situation, it's not surprising that experts estimate that millions of Windows computers worldwide are infected with some type of worm.