Successful prosecution
Known in the industry as a "denial of service" attack, the mass e-mails not only collapsed the server and the router but caused the firm to lose an estimated £30,000.
DCI Charlie McMurdie, head of the Metropolitan Police's Computer Crime Unit, said: "This is the first successful prosecution in the UK for this type of offence.
"This demonstrates the commitment of the MPS Computer Crime Unit to work with industry to prosecute individuals who use technology to cause harm."
The mail server was responsible for processing the company's e-mails in the UK, Germany, Spain and France.
Lennon's e-mails purported to originate from company employees, including Microsoft head, Bill Gates.
They contained a quote from the horror film The Ring.
