function valid(){

var reg = /^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]{2,}[.][a-zA-Z]{2,4}$/

if(document.forms["msg"].nom.value == ""){
		alert("Name field is empty");
		document.forms['msg'].nom.focus();
		return false;
	}else if(document.forms['msg'].prenom.value == ""){
		alert('First name field is empty');
		document.forms['msg'].prenom.focus();
		return false;
	}else if (reg.exec(document.forms[1].mail.value)==null){
		alert('Email field is empty or invalid');
		document.forms['msg'].mail.focus();
		return false;
	}else if(document.forms['msg'].comments.value == ""){
		alert('Comments field is empty');
		document.forms['msg'].comments.focus();
		return false;
	}else{
		return true;	
	}
}