The email, posted by Open Source Initiative on its website, was sent on 12 October from Michael Anderer, CEO of S2 Partners to SCO vice president Chris Sontag and chief financial officer Robert Bench. It appears to discuss compensation to the value of $86 million from Microsoft that Anderer received for facilitating funding deals on SCO’s behalf.

The email provides evidence for those in the software industry who suspect Microsoft of indirectly funding SCO’s copyright infringement campaign against Linux. Eric Raymond, an open-source software guru, described the email as a “smoking gun”.

SCO, while acknowledging the email, dismissed both the author’s and Raymond’s conclusions. “We believe the email was simply a misunderstanding of the facts by an outside consultant who was working on a specific unrelated project,” said SCO spokesman Blake Stowell. Anderer was not available for comment.

SCO had originally claimed that millions of lines of code had been copied from its Unix operating systems directly into Linux. It is currently demanding $699 in intellectual property fees for a single-processor Linux server.

SCO has now started to take its campaign directly to users of Linux, by bringing legal action against a number of high-profile users. This week, it started proceedings against DaimlerChrysler and US car parts retailer AutoZone and it also appears to have prepared a complaint against Bank of America.

This was disclosed when a document detailing SCO’s case against DaimlerChrysler named the bank as the defendant. The mistake was discovered through the Microsoft Word feature that allows users to track changes.

At the same time, three more companies — Leggett &Platt, Queststar and Computer Associates — have purchased licences, SCO has disclosed, allowing them to run Linux without fear that SCO will take legal action against them.

Computer Associates has stated its disapproval of SCO’s tactics despite buying the licence. “CA disagrees with SCO’s tactics, which are intended to intimidate and threaten customers,” said Sam Greenblatt, senior vice president of CA’s Linux technology Group in a statement. “CA’s license for Linux technology is part of a larger settlement with the Canopy Group.”