The episode serves as an alarming reminder of the challenges involved in dealing with spammers and the resources they have at their disposal to deter those trying to stop them, analyst said.

In a statement Tuesday, Blue Security, which has its U.S. headquarters in Meno Park Calif., said it can no longer "take the responsibility for an ever-escalating cyber war through our continued operations.

"As we cannot build the Blue Security business on the foundation we originally envisioned, we are discontinuing all of our anti-spam activities on your behalf and are exploring other, non-spam-related avenues for our technological developments," the company said.

The decision comes only days after Blue Security re-started operations following a massive and sustained denial of service (DoS) attack launched against it by PharmaMaster earlier this month.

Blue Security operated a fairly controversial antispam service designed to deter junk-mailers by spamming them back. Blue Security's Do Not Intrude program allowed individuals to register their e-mail addresses with the company and essentially flood spammers who sent them e-mail with automated opt-out requests.