Apple is one of 36 companies being sued for spam email filtering. InNova claims they invented the technology first.

InNova filed for a lawsuit against a number of well known technology firms including Apple, Google, Dell and Yahoo, claiming the companies have been using their spam filtering invention without permission for years.

The InNova patent was granted to Robert Uomini, an inventor and mathematician, fifteen years ago when email was still in it's early stages. The patent covers technology used to differentiate between spam email messages and those that users actually want to receive. Uomini is the founder of InNova, however, InNova is a company specialising in patent licensing.

"More than 80 percent of email is spam, which is why companies use InNova's invention rather than forcing employees to wade through billions of useless emails. Unfortunately, the defendants appear to be profiting from this invention without any consideration for InNova's legal patent rights," said patent-infringement attorney Christopher Banys in a press release.

None of the companies involved have yet responded to the lawsuit.