The argument they make is that it's OK because they got your details from a "public" data source, plus guesswork. E.g. LinkedIn plus your company domain. They're still supposed to notify you when your info was transferred to them though.

The problem is that this is in breach of LinkedIn terms and conditions, which means I immediately write off the company: if they can't lawfully find marketing leads, which should I trust them to lawfully process my business data.