You have to modify the sender's public-key certificate, make sure the sender would have a copy of that and modify the recipient's key as well, Jones says.

CNN: Technology - Security flaw discovered in Network Associates PGP software

Its speediness results from its ability to trigger the recipient's e-mail program to send a copy of itself to everyone listed in the program's address book.

CNN: 'Melissa' May Have Built a False Sense of Security