function echeck(str) {

  var at="@"
  var dot="."
  var lat=str.indexOf(at)
  var lstr=str.length
  var ldot=str.indexOf(dot)
  if (str.indexOf(at)==-1)
  {     
     return false
  }

  if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr)
  {     
     return false
  }

  if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
      
      return false
  }

   if (str.indexOf(at,(lat+1))!=-1){
      
      return false
   }

  if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
      
      return false
   }

   if (str.indexOf(dot,(lat+2))==-1){
      
      return false
   }
  
   if (str.indexOf(" ")!=-1){
      
      return false
   }

    return true     
 }


function thisform_onsubmit() { 

if(thisform.Name.value  == ""
 || thisform.EmailAddress.value  == ""
 || thisform.Message .value == "")
{ 
alert('Please enter the required fields marked with a red star!'); 
return false; 
} 


if(thisform.EmailAddress.value != "")
{
 if(!echeck(thisform.EmailAddress.value))
 {
 alert('The email is invalid. Please enter a valid email!');
 document.thisform.EmailAddress.focus();
 return false; 
 }
}

return true; 

}