I already saw this spam a lot of times, but this time I decided to look a bit more into it. Some “Spanish” company (with its domain registered with a Chinese domain provider and a site hosted in Romania) is sending “update forms” for people to fill, sign and send back. They make the payment part non-obvious by stating in bold “updating is free of charge”, but in the small print, you’ll see that “by signing you subscribe for 3 years”, “subscription is automatically renewed every year” and “it costs 995€/year”.
So, if you are dumb enough to just look at the document, fill and sign (hey, it’s free), you’ll receive a nice invoice soon after (hey nice, you signed to pay 995€/year, we got your acceptance here!).
I’m not a lawyer, however I guess they can’t legally do anything as the document is misleading, sent as spam and does not clearly state the company handling it (neither do their website), so if you signed it, you are most likely safe not paying them (it should be possible to sue them for misleading offer or something in front of an EU court, but most likely not in Spain anyway).
In the meantime you can browse http://www.eubusinessregister.com/ and laugh at those who were dumb enough to sign and get their company inserted in there for 995€/year.