function check_email(e) {
	ok = "1234567890qwertyuiop[]asdfghjklzxcvbnm.@-_QWERTYUIOPASDFGHJKLZXCVBNM";
	
	for(i=0; i < e.length ;i++){
		if(ok.indexOf(e.charAt(i))<0){ 
			return (false);
		}	
	} 
	
	if (document.images) {
		re = /(@.*@)|(\.\.)|(^\.)|(^@)|(@$)|(\.$)|(@\.)/;
		re_two = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/;
		if (!e.match(re) && e.match(re_two)) {
			return (-1);		
		} 
	
	}

}

function checkform(){
	var name = document.getElementById('name');
	var company = document.getElementById('company');
	var phone = document.getElementById('phone');
	var email = document.getElementById('email');
	var comment = document.getElementById('comment');

	if( email.value.length < 5 ){ 
		alert('Dirección de Email demasiado corta.');
		email.focus();
		return false;
	}else{
		if( check_email(email.value) ){
			if( comment.value.length == 0 ){
				alert('El campo de observaciones no puede estar vacío.');
				comment.focus();
				return false;
			}else{
				return true;
			}
		}else{
			alert('Formato de email incorrecto.');
			email.focus();
			return false;
		}
	}
}