function checkmail()
{
     var email     = document.getElementById('email').value;
     var verif     = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]{2,}[.][a-zA-Z]{2,3}$/

        if (verif.exec(email) == null)
     {
                        alert('email invalide.');
         return false;
     }
     else
     {
         return true;
     }
}


function clearmail()
{
	var email     = document.getElementById('email').value;
	if ( email = 'adresse' ) document.getElementById('email').value='';
}