Paul Smith, who founded HU17.net, complained to the Press Complaints Commission that articles headlined "Town website publisher's porn business", "The sickening porn behind this man's veil of respectability" and "Town website: the sordid truth", published in March, were inaccurate and misleading.
Following their investigation, the commission said that while there was "legitimate public interest" for the newspaper to examine Smith's activities given his role as a community website publisher, "such high-profile scrutiny carried with it the responsibility to be accurate".
According to the adjudication report, Smith told the commission he had only ever designed "a hundred or so websites", including some adult sites, and that he had bought just over 100 domain names, nearly half of which were dormant.
The newspaper responded that, at the time of its investigation a web registration search showed that the complainant owned 3,991 domains under the name Smiths Media Solutions, the majority of which could be categorised as adult.
The paper also said that Smith had been contacted prior to publication to respond, but was unable to confirm the number and did not deny the allegation.
Following publication of the articles, the newspaper claims the relevant server was disconnected and as a result it was unable to prove the figure.
As the Mail was unable to substantiate its claims, the commission found that readers would have been misled as to the scale of the complainant's involvement and as such the articles did breach Clause 1 of the Editors' Code of Conduct.
Despite the ruling, at the time of publication at least one of the Mail's articles is still available online.
Other complaints by Smith, including allegations that the coverage was intrusive and that the newspaper had used subterfuge were not upheld due to a public interest defence.
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