It is 100% real. I read this yesterday and thought it was fake, however after calling support i got an email asking the same thing. The email quoted in this thread is not the FULL email though, the actual email states, and i quote:

Dear XXXX,

Thank you for contacting the Square Enix Support Centre.


We are contacting you regarding your issues when trying to register a payment method.

Please send us a picture of the card to sel-id@square-enix.com mentioning ticket number XXXXXX, as we require this for ownership verification purposes.

IMPORTANT: We only need the name and last four digits on the card - please black out all other information as we cannot store our customers' credit card information for security reasons. Any pictures showing the full card face will be immediatly deleted from our systems and we would have to re-request an appropriate picture.

In addition, we would like you to make sure that you have sufficient funds on your account.

We apologise for the inconvenience.