Broadband users from across the UK have received letters accusing them of illegal file sharing relating to adult movie titles.
German firm DigiProtect has hit providers with court orders over the alleged illicit downloads made by their subscribers, forcing the ISPs to release customer details.
Broadband contract holders have been sent a lengthy legal letter asking them to pay a £500 settlement fee or face a court appearance.
A solicitor representing some of the individuals accused told the BBC: "It's the embarrassment factor. One lady told us she fainted when she opened her letter.
"Teenagers right up to old-age pensioners have been accused of downloading hardcore porn. The overriding feeling is one of outrage."
One of the highest profile cases has involved a Hertfordshire couple in their 60s who had been accused of illegal file sharing, when they claim to have no knowledge of how to download.