An online market research company has accidentally sent the email addresses of around 13,000 of its subscribers to what appears to be its entire UK mailing list.
The company, Netherlands-based OpinionWorld, included the addresses as plain text in the main body of the messages, which were sent out last night.
The email has the subject line: "Let your voice be heard, a small survey by Opinionworld".
A spokesman for the UK's Information Commissioner said that this "almost certainly" contravenes the Data Protection Act, but described it as an "unintentional cock-up" rather than a serious or deliberate breach of the legislation. But people whose addresses are on the list are worried that the mail could be exploited by spammers.
One silicon.com reader, Frankie Hipwell-Larkin, technical director of Acclaiminternet, was sent the mass mail to his business address.
He said: "When I saw this in my in-box I thought: 'Hang on, this is not for me.' Then I realised what it was, did a search under my email address and found that it was among the list of names."
He added: "Unsolicited mail is an awful thing at the best of times. Am I to expect spam from wherever now?"
Hipwell-Larkin had participated in one survey conducted by OpinionWorld on behalf of the NSPCC.
OpinionWorld asks people to volunteer to take part in its online polls, which are conducted about once a month. The subjects vary from societal issues, new products and services, TV shows and commercials, and the Internet. It claims its clients include businesses, governments and charities.
OpinionWorld's Web site suggests that it takes privacy seriously. It is registered with something called the Registration Board and is a member of ESOMAR (World Association of Opinion and Marketing Research) and conforms to the ICC/ESOMAR code of conduct for research.
OpinionWorld failed to respond to our requests for comment. ESOMAR did not immediately respond to requests for comment.