It's not the first time I've seen this clause...
...it also was on Renfe's quite useless website, the Spanish state-owned railway company. Even more, it explicitly requested permission from them to include a link to their website on e-mails. Yes, e-mails.
So I sent them an e-mail requesting permission. Never got a reply.
Now that I think about it, was that e-mail itself a breach of the conditions becasue I sent to somewhere at renfe.com (which included the forbidden renfe.com) before asking permission from them by e-mail? Should I had written a prior e-mail asking for permission to send them an e-mail asking for permission? And what about this e-mail?