In its April 2010 security report, Symantec said it has detected 36,208 unique strains of malware that were designed to carry out targeted attacks.

MessageLabs, which was acquired by Symantec later, was the first one to raise the alert on the Love Bug virus, which was designed to overwrite and destroy data. The virus came in the form of a message attachment when, once opened, sent itself to the addresses of the email recipient and spread on from there.

Ten years since Symantec Hosted Services, then MessageLabs, intercepted 13,000 copies of the virus in a single day on 4 May 2000, MessageLabs Intelligence said it now stops 1.5 million copies of malicious e-mails each day.

"Although mass mailing viruses like the Love Bug are rare today, cyber criminals' techniques have evolved to more malicious, highly targeted attacks and they are motivated less by achievement and credibility than by financial gain and identity theft," Symantec said in a statement. "On 4 May, 2000, 1 in 28 e-mails contained the Love Bug virus. By comparison, 1 in 287.2 e-mails contained a virus on 9 April 2010, the peak for April. In April 2010 overall, MessageLabs Intelligence intercepted 36,208 unique strains of malware."

"The Love Bug was operating in the wake of the Melissa virus, a similarly destructive worm from the previous year," said MessageLabs Intelligence senior analyst Paul Wood. "Back then, users were less savvy, regarding the dangers posed by suspicious e-mail attachments and e-mails from unknown senders. The general public was also less aware of issues such as spam and denial of service attacks."