function check_form(form)
{
var str=form.email.value
var filter=/^.+@.+\..{2,3}$/

if(form.name.value=='')
{
alert("Please Enter your Name.");
form.name.focus();
return false;
}else if (!filter.test(str))
{
 alert("Please input a valid email address!")
 form.email.focus();
return false;
}

if(form.message.value=='')
{
alert("Please type your message.");
form.message.focus();
return false;
}
return true;

}