Cloudmark has flagged as suspicious about 80 percent of the IP space belonging to Panamaserver.com, which allows people to pay for hosting services with a higher degree of privacy using payment services such as Web Money or Liberty reserve, Conway said. Cloudmark's customers can decide whether they want to actually block content coming from those flagged IP addresses.
The email spam seen originating from its IP block targets people in Brazil. Conway said there is no antispam law in Brazil, but Cloudmark does flag the messages as suspect.
In the last two months, Cloudmark saw a major spam run from Romania using IPv6, an Internet specification that dramatically expands the number of IP addresses. But the problem is that IPv6 addresses are so plentiful that blocking an individual address has little effect on spam.
Conway said it's better for antispam products to throttle the number of messages that can be received from a block of IPv6 addresses. Cloudmark already flags 3.3 million of Romania's 14 million IPv4 addresses as having a reputation for spam, Conway said.
As it becomes more difficult to send spam from Romania, Conway said there are signs spammers may be using IP addresses in Belarus. "Spammers will follow the line of least resistance," he said.
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