The report concluded that in May, the percentage of junk mail jumped 5.1 percent to 90.4 percent. Most of the messages contain nothing more than a subject line and a hyperlink. In many of the cases, the links led to social-networking site profiles, which the spammers likely created en masse by using automated CAPTCHA-breaking tools. The pages typically hawked weight-loss medication.
What makes this spamming technique successful is that the emails are sent from valid accounts hosted by the social-networking provider, according to the report.
"The emails were not being spoofed, as was often the case for these types of domains in the past," the report said. "Techniques to check the validity of these headers are ineffective as anti-spam countermeasures, as all they will establish is that the sender is genuine and not spoofed or sent from a botnet."
The most pronounced rise occurred in Hong Kong, where 92.3 percent of all email is unsolicited, making that city the most spammed locale. China, the UK, Australia and Japan round out the top five. About 87 percent of email in the United States is spam.
The amount of unwanted email shows no signs of stopping. Cisco IronPort detected 249 billion spam messages in a 24 hour period ending Tuesday, amounting to the third-largest junk mail run on record, Nilesh Bhandari, a product manager at Cisco IronPort told SCMagazine on Tuesday. He blamed botnets such as Rustock and Pushdo for the increasing spam.
A portion of unwanted email currently making the rounds is related to a new take on image spam, in which junk mailers package their messages as part of an image file, thus making it more difficult for filters to detect, according to the Symantec report. The new trend, according to the report, is to use Russian language character sets to hide English-language content.