The most basic form of spam—a high volume of unsolicited bulk email that is sent from a single IP address—is easily detected and blocked by anti-spam technology today. Snowshoe spam is a new variation on this theme.
Think of a real snowshoe, which distributes a person’s weight over a broader area than just a person’s own feet, making it less likely to sink into the snow. With snowshoe spam, the same basic premise is in use, but instead of distributing weight across a broader area, spammers distribute their IP address footprint. Snowshoe spammers spread their message over many different IP addresses, each used in low volume, to send the message.
According to research from Cisco, snowshoe spam grew from 7 percent of the total volume of spam in November 2013 to 15 percent in April 2014.