semisonix on "[Plugin: Contact Form 7] CF7 displays nicely, but "failed to send the message""

Hi all,

Using CF7 for a long time, and first time I get this error.
[blockquote]
Failed to send your message. Please try later or contact the administrator by another method.[/blockquote]

The forms displays nicely, but cannot get it to work.

http://theoldmanandtheseaaruba.com/reservations/
http://theoldmanandtheseaaruba.com/contact-us/

http://wordpress.org/extend/plugins/contact-form-7/