A small javascript file to extract from, to and envelope-to from a mail header. Used at www.spambarrier.de

header.html

<script type="text/javascript">
function validate()
{
const regexpEnvelope = /envelope-from.*/g;
const regexpFrom = /From:.*>/g;
const regexpTo = /\nTo: .*/g;
var headerText = document.getElementById("txt").value;
const matchesEnvelope = headerText.matchAll(regexpEnvelope);
const matchesFrom = headerText.matchAll(regexpFrom);
const matchesTo = headerText.matchAll(regexpTo);
var from = "";
var to = "";
var envelope = "";
var my_html = "";

for (const match of matchesEnvelope) 
{ 
	var text = match.toString().replace('(envelope-from ','').replace(">)","");
	var lookingFor = '<';
	var replaced = text.substring(text.indexOf(lookingFor) + lookingFor.length);
	my_html = my_html + "Envelope: " + replaced; 
  envelope = replaced;
}

my_html = my_html + "<br/>";

    
for (const match of matchesFrom) 
{ 
	var text = match.toString().replace('From: ','').replace(">","");
	var lookingFor = '<';
	var replaced = text.substring(text.indexOf(lookingFor) + lookingFor.length);
	my_html = my_html + "From: " + replaced; 
  from = replaced;
}

my_html = my_html + "<br/>";

for (const match of matchesTo) 
{
	if (match.toString().includes("quarantine") == false)
	{
	var text = match.toString().replace('To: ','').replace(">","");
	var lookingFor = '<';
	var replaced = text.substring(text.indexOf(lookingFor) + lookingFor.length);
	my_html = my_html + "To: " + replaced + "<br/>" ; 
  to = replaced;
	}
}

my_html = my_html + "<br/>";
my_html = my_html + "Bitte legen Sie folgende Whitelist-Eintr&auml;ge an:<br/>";
my_html = my_html + "Von: " + from + " - An: " + to + "<br/>";
my_html = my_html + "Von: " + envelope + " - An: " + to + "<br/>";

var container = document.getElementById('container');
container.innerHTML = my_html;
return false;
}
function printDiv(divName) {
     var printContents = document.getElementById(divName).innerHTML;
     var originalContents = document.body.innerHTML;

     document.body.innerHTML = printContents;

     window.print();

     document.body.innerHTML = originalContents;
}
</script>

<form action="" method="post" onsubmit="return validate()">
<textarea id="txt" name="txt" cols="100" rows="10">Bitte Header hier einfügen</textarea><br>
<input type="submit" value="Absender ermitteln">
</form>
<div id="container"></div>