Malware was in the minor leagues before Melissa showed everyone how to really harass the Internet. 10 years later we still don't have a good solution to mail worms.
It was the first of the mail viruses.
Melissa hit the scene in March of 1999 and seemed a little like black magic. Open an e-mail attachment, from someone you know, no less, and suddenly other people you know are getting the same e-mail. Melissa required Microsoft Office, Word and Outlook in particular, using VBA for programming and MAPI for transport. Some modifications were needed to the model, but the mail virus was an inspiration which transformed the world of malware and went on to build the massive populations of botnets that infect and persecute the world.