Melissa was the 1999 computer virus spread through Microsoft Word documents that targeted users’ address books.
The virus was distributed in a document attached to email messages, often with the subject “Important Message From” followed by the sender’s name. When opened in a compatible version of Microsoft Word, its macro code attempted to forward itself to the first 50 addresses in Microsoft Outlook’s address book.
The sudden volume of outgoing mail overloaded email systems at many organizations. Melissa also modified Word documents by inserting text, but its most memorable effect was the automated mass mailing that turned ordinary users into unwitting distributors.
Melissa is commonly called a virus because it infected documents and relied on macro behavior, while ILOVEYOU is generally classified as a worm or Trojan-like script. Both used social trust and email, but they appeared one year apart and used different technical mechanisms.