As spammers find their e-mails blocked, they are trying other tactics. Expect no respite

WHEN Mark Zuckerberg, the boss of Facebook, presented its new messaging service on November 15th, he praised one feature in particular: the “social inbox”, which would catch spam or other unwanted messages. “Because we know who your friends are, we can put in really good filters to make sure you only see things you care about,” he said, with unwarranted confidence.

Spammers are moving onto social-networking sites such as Facebook because they find e-mail increasingly unrewarding. Data from Cisco, which makes networking gear, show the volume of e-mail spam began declining slowly in late 2009 (see chart) and by almost half in the past three months, after the authorities disabled spam networks in Russia and the Netherlands. …