Google has definitely acquired anti-spam startup Impermium, CBR can reveal, after confusion over the nature of the deal.

The search engine giant announced the move last night, but observers were left in the dark over whether it was an outright takeover or what is known as an ‘acqui-hire’, where the staff are taken on and operations shut down.

The three-year-old company will now wind down contracts of existing customers, CBR understands, following questions over what would happen to those customers’ services now Impermium effectively ceases to exist.

People visiting the business’s site found only a blog post from CEO Mark Risher.

He said: "By joining Google, our team will merge with some of the best abuse fighters in the world. With our combined talents we’ll be able to further our mission and help make the Internet a safer place."

Google’s only announcement about the deal was Google+ product VP Bradley Horowitz’s post, which read: "Google’s spam and abuse teams are industry-leading and world-class. Impermium should fit right in."

The sum of the deal remains unknown, but the search engine giant recently acquired home automation firm Nest Labs for $3.2bn.