Charny, Ben. E-mail tracking firm says it didn't know of H-P link. MarketWatch Oct. 3, 2006.

E-mail tracking firm says it didn't know of H-P link - MarketWatch Interesting anecdote to HP story that's been in the news ... they used ReadNotify (software that tracks whether a message has been read, even when sent across the Internet) in an attempt to spy on a reporter ... the rest is history. David