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("Ongeldig E-mailadres")
		   return false
		}

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

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

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

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

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

 		 return true					
	}

function ValidateForm(){
	var emailID=document.form.Email
	
	if ((emailID.value==null)||(emailID.value=="")){
		alert("Ongeldig E-mailadres")
		emailID.focus()
		return false
	}
	if (echeck(emailID.value)==false){
		emailID.value=""
		emailID.focus()
		return false
	}
	verify();
	
 }


function verify() {
var themessage = "De volgende velden zijn verplicht: ";
if (document.form.NaamOnderneming.value=="") {
themessage = themessage + " - Naam Onderneming";
}
if (document.form.NaamContactpersoon.value=="") {
themessage = themessage + " -  Naam Contactpersoon";
}
if (document.form.Vestigingsadres.value=="") {
themessage = themessage + " -  Adres";
}
if (document.form.PCPlaats.value=="") {
themessage = themessage + " -  Postcode/plaats";
}
if (document.form.Telefoon.value=="") {
themessage = themessage + " -  Telefoon";
}
if (document.form.Email.value=="") {
themessage = themessage + " -  E-mail";
}

//alert if fields are empty and cancel form submit
if (themessage == "De volgende velden zijn verplicht: ") {
document.form.submit();
}
else {
alert(themessage);
return false;
   }
}