function chkFormular()
{
 if(document.mail.Mail.value == "") {
   alert("Please insert your e-mail-address!");
   document.mail.Mail.focus();
   return false;
 }
 
 if(document.mail.Mail.value.indexOf('@') == -1) {
   alert("No valid e-mail-address!");
   document.mail.Mail.focus();
   return false;
 }
}

function focus()
{
 document.mail.Name.focus();
}