function fcheck(form_id,email) {
   var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
   var address = document.forms[form_id].elements[email].value;
   if(reg.test(address) == false) {
      alert('Invalid E-mail ID');
      return false;
   }
}
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){
	   alert("Invalid E-mail ID")
	   return false
	}

	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
	   alert("Invalid E-mail ID")
	   return false
	}

	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
		alert("Invalid E-mail ID")
		return false
	}

	 if (str.indexOf(at,(lat+1))!=-1){
		alert("Invalid E-mail ID")
		return false
	 }

	 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
		alert("Invalid E-mail ID")
		return false
	 }

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

	 return true					
}

function validateForm(form) { //This is the name of the function
if (form.email.value == "") { //This checks to make sure the field is not empty
   alert("An email address is required to process this form."); //Informs user of empty field
   form.email.focus( ); //This focuses the cursor on the empty field
   return false; //This prevents the form from being submitted
   }   
if (echeck(form.email.value)==false){
	form.email.value=""
	form.email.focus()
	return false;
	}
if (fcheck('form1', 'email')==false){
	form.email.value=""
	form.email.focus()
	return false;
	}
}