By Sean Gallgher | ArsTechnica | Apr. 21, 2012

Agents of the Federal Bureau of Investigations seized a server belonging to an Italian Internet service provider on Thursday as part of an investigation into a series of anonymous bomb threats sent to the University of Pittsburgh. But the groups associated with the operation of the server are calling the seizure an attack on Internet anonymity.

The server that was seized belongs to the Italian political activist Internet service European Counter Network, and hosted a node of the Mixmaster anonymous remailer service. It was seized under a search warrant served on a co-location facility in New York shared by Riseup networks (a "technology collective" that provides secure communciations for activists) and May First/People Link (an Internet co-op). The server also provided e-mail and other services to ECN's users.

According to a statement from Riseup Networks, the server hosted several websites, over 300 e-mail accounts, and as many as 80 e-mail discussion lists—including an Italian "cyber rights" listserv and discussion lists for Mexican migrant, labor and indigenous peoples' rights groups. May First/People Link Director Jamie McClelland said in a statement that "the server seizure is not only an attack against us, but an attack against all users of the Internet who depend on anonymous communication."

Because the server was just one node in the Mixmaster remailer network, which anonymizes e-mails in much the same way that the TOR Network anonymizes website visits, the members of Riseup and May First/People Link say that there's little chance that the FBI will be able to determine the source of the e-mail from forensic analysis of the server. "Taking this server won’t stop these bomb threats," said Riseup spokesperson Devin Thierot-Orr. "The network of anonymous remailers that exists is not harmed by taking this machine. So we cannot help but wonder why such drastic action was taken when authorities knew that the server contained no useful information that would help in their investigation.”

Since the server seizure, the Associated Press reports, at least six more anonymous e-mailed bomb threats have been received by the University of Pittsburgh.