[Plugin: Contact Form 7] sending the title of the email twice

Hello,

I’m having problem sending the most simple contact form. Sometimes it does not reach the recipient. The host (OVH – very bad French host) is saying that forms from the site send the title of the email twice which is why it is flittered by their server.

They tried to send the email with this script and it worked:

<?php
    mail('email_destinataire', 'sujet', 'message');
?>

I can’t understand this. I have used Contact Form 7 with WordPress on many, many sites on many, many hosts.

Has anyone come across this problem before.