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State Seal KY Long-Term Policy Research Center
States Creating Anti-Spam Registries Should Expect More Spam
Press Release Date:  May 25, 2005

Mark Schirmer (


In an effort to combat the ongoing nuisance of unsolicited bulk e-mail, legislators in a number of states are moving forward with plans for statewide do-not-spam registries, similar to the national do-not-call list telemarketers must respect. But a study published by the Kentucky Long-Term Policy Research Center offers strong evidence that these states should expect to receive more spam. What’s more, the federal CAN-SPAM legislation, though it has played a role in a series of prosecutions, has been an ineffective deterrent against spam.

In a test conducted from February to December of 2004, Center researcher Mark Schirmer operated a series of e-mail addresses hidden on several government Web sites. Though invisible to people browsing the sites, software used by spammers to harvest e-mail addresses would have no trouble finding them. Within days of going online, the addresses began receiving spam—in violation of the federal prohibition against the harvesting—and the volume of incoming e-mails skyrocketed over the course of the year (see Figure 1).

Figure 1:  Number of Spam E-Mails Received per Month, February to December 2004

For one group of e-mail addresses, Mr. Schirmer placed opt-out requests for each piece of spam; he made no reply for a comparison group of addresses. The two groups received nearly identical quantities of spam for the first three months, but they began diverging dramatically in May. From that point forward, the opt-out addresses received increasingly more bulk e-mails than the no reply group. By year’s end, the opt-outs incurred triple the amount of spam each week as the no reply addresses (see Figure 2).

Figure 2:  The Outcome of Opting-Out

An additional e-mail address included in the study was never posted online: harvesters had no way of finding it, and the address received no spam for the first four months. But in June, Mr. Schirmer began submitting this address to Web-based opt-out mechanisms when attempting to unsubscribe the opt-out addresses. Within days, the unlisted e-mail account began receiving spam. From July forward, this unlisted address was bombarded by more spam than the no reply average (see Figure 2).

The spam study is presented in the current edition of the Center’s free publication, Foresight, which is available on the Web or by request from the agency at 502-564-2851 or 800-853-2851.


Last updated: Thursday, May 26, 2005