function checkemail(input)
{
   if (input.value=="" ||input.value==null)
      {
            alert("Please enter a valid email address.");
            input.focus();
            return false;
      }
   else
      {
         apos=input.value.indexOf("@");
         dotpos=input.value.lastIndexOf(".");
         if (apos<1||dotpos-apos<2)
         {
            alert("Please enter a valid email address.");
            input.focus();
	    input.select();
            return false;
         }
      else 
         {
            return true;
         }
      }
}