`emailrelay-edit-envelope.js <emailrelay-edit-envelope.js>`_
------------------------------------------------------------

.. code:: javascript

    //
    // SPDX-FileCopyrightText: 2026 Graeme Walker <graeme_walker@users.sourceforge.net>
    // SPDX-License-Identifier: FSFAP
    // 
    // Copyright (c) 2026 Graeme Walker <graeme_walker@users.sourceforge.net>
    // 
    // Copying and distribution of this file, with or without modification,
    // are permitted in any medium without royalty provided the copyright
    // notice and this notice are preserved.  This file is offered as-is,
    // without any warranty.
    // ===
    //
    // emailrelay-edit-envelope.js
    //
    // An example E-MailRelay filter script for Windows that
    // edits the message's envelope file.
    //
    // In this example the "MailFromAuthOut" field in the
    // envelope file is modified; this is used as the MAIL FROM
    // AUTH parameter when the emailrelay server forwards the
    // message to the downstream server. In principle (RFC-2554)
    // when relaying the outgoing MAIL FROM AUTH value should
    // be the same as the incoming value iff the submitting
    // client was authenticated and trusted; or it can be the
    // submitting client's authentication id if there was no
    // incoming value; or it can be "<>".
    //
    try
    {
    	// parse the command-line to get the envelope filename
    	var content = WScript.Arguments(0) ;
    	var envelope = WScript.Arguments(1) ;
    
    	// open the envelope file
    	var fs = WScript.CreateObject( "Scripting.FileSystemObject" ) ;
    	var ts = fs.OpenTextFile( envelope , 1 , false ) ;
    
    	// read the contents of the envelope file
    	var txt = ts.ReadAll() ;
    	ts.Close() ;
    
    	// read the incoming values
    	var re_auth_in = new RegExp( "^X-MailRelay-MailFromAuthIn: *(\\S*)" , "m" ) ;
    	txt.match( re_auth_in ) ;
    	var auth_in = RegExp.lastParen ;
    	var re_authentication = new RegExp( "^X-MailRelay-Authentication: *(\\S*)" , "m" ) ;
    	txt.match( re_authentication ) ;
    	var authentication = RegExp.lastParen ;
    
    	// choose the auth-out value
    	var auth_out = "<>" ;
    	if( authentication )
    	{
    		function xtext( x ) { return x } // todo
    		auth_out = auth_in ? auth_in : xtext(authentication) ;
    	}
    
    	// set the auth-out
    	var re = new RegExp( "X-MailRelay-MailFromAuthOut: *\\S*" ) ;
    	txt = txt.replace( re , "X-MailRelay-MailFromAuthOut: " + auth_out ) ;
    
    	// write the envelope file back out
    	ts = fs.OpenTextFile( envelope , 2 , false ) ;
    	ts.Write( txt ) ;
    	ts.Close() ;
    
    	// successful exit
    	WScript.Quit( 0 ) ;
    }
    catch( e )
    {
    	// report errors using the special <<...>> markers
    	WScript.StdOut.WriteLine( "<<edit failed>>" ) ;
    	WScript.StdOut.WriteLine( "<<" + e + ">>" ) ;
    	WScript.Quit( 1 ) ;
    }

.. _../examples/emailrelay-edit-envelope.js: emailrelay-edit-envelope_js.html