function validate_required(field,alerttxt)
{
with (field)
{
if (value==null||value=="")
  {alert(alerttxt);return false;}
else {return true}
}
}function validate_form(thisform)
{
with (thisform)
{
if (validate_required(name,"Please enter your name.")==false)
  {name.focus();return false;}
if (validate_email(email,"Please enter a valid email address.")==false)
  {email.focus();return false;}
if (validate_required(message,"Please enter your message.")==false)
  {message.focus();return false;}
}
}

function validate_email(field,alerttxt)
{
with (field)
{
apos=value.indexOf("@");
dotpos=value.lastIndexOf(".");
if (apos<1||dotpos-apos<2) 
  {alert(alerttxt);return false;}
else {return true;}
}
}