function popupform(myform, windowname)
{
 a = document.newslettre.email_address_newslettre.value;
 valide1 = false;
	
	for(var j=1;j<(a.length);j++){
		if(a.charAt(j)=='@'){
			if(j<(a.length-4)){
				for(var k=j;k<(a.length-2);k++){
					if(a.charAt(k)=='.') valide1=true;
				}
			}
		}
	}
  if(valide1){ 
if (! window.focus)return true;
window.open('', windowname, 'height=200,width=400,scrollbars=yes');
myform.target=windowname;
document.newslettre.email_address_newslettre.value='';
return true;
}
else{
    alert("Veuillez saisir une adresse email valide.");
	return false;

}
}