the Melissa virus
loresecurity
The March 1999 Word-macro virus that mailed itself to the first 50 Outlook contacts and buried corporate email worldwide.
David L. Smith released Melissa on March 26, 1999, hiding it in a Word document; each opened copy mass-mailed itself onward, and the exponential flood forced companies including Microsoft to shut off outbound email. Smith, who named it after a dancer, was traced within days and sentenced to prison. Melissa marked the moment email itself became the malware transport of choice.